Hi Seateasea,
I am sorry that you had cause to go looking for this place, but I am glad that you found it. There are many people here who have been through similar things, all of whom were just as lost as you feel at the moment, and all of whom got through it, one way or the other.
There is a resource here that others have mentioned called The Healing Library:
http://www.survivinginfidelity.com/articles.asp
Please do spend some time looking through it, there is a lot of accumulated experience and wisdom there.
To try and help you get a handle on things, I have a few things to say. Although the details you post are quiet brief, it seems like your wife has a 'wayward' way of thinking. 'Wayward' is a term used here for people who commit infidelity. My reasons for saying this are because she did several 'classic' things that waywards do.
The first classic wayward action is minimising, which she did in relation to going out with her married friend, getting picked up, and going to a park with some random stranger. You say that, "She told me over and over again that nothing happened", but she was a married woman, just two years into her marriage, and she was going out cruising with a married friend, allowing herself to be picked up, and going to a park with some guy she didn't know from Adam. And yet she describes those actions as "nothing", because - presumably - none of it matters if she didn't have sex with the guy.
Leaving aside the actual details of their interaction at the park, why was she being picked up, why was she going to a park with a stranger, and why was she letting him undress her? That is not nothing, and she is minimising to try and brush over it that way.
Your wife then engaged in another 'classic' wayward behaviour, which is called trickle-truthing. That is the process where elements of a story are revealed bit by bit, little by little, as time passes.
My wife went with one of the men to a local park where they had made out.She told me of this a few days after it happened. She told me that they just kissed. A week later she told me that he had undone her pants and placed his hands on her butt, but that is all.
Frequently, trickle-truthing is shortened to 'TT' in this forum. It is a thing that can go on for years in some cases, and it makes it very hard for a betrayed spouse to ever feel like they have got the complete truth. It could be argued that waiting thirty-four years before revealing the affair was an extreme case of trickle-truthing, but there are quite a few cases in these forums where affairs have only come to light after decades of being hidden.
Due to the fact that so many waywards use minimising and trickle-truth, many here who have read a lot of cases will doubt that your wife's account of how limited the interaction in the park is likely to be the whole story. It does seem hard to believe that two adults would go to a park to engage in sexual activity and then simply stop. However, simply going out, getting picked up, and ending up in a state of semi-undress with some random man was an act of cheating, not "nothing".
Following those events, your wife then engaged in another 'classic' wayward behaviour, which is blame-shifting:
I became depressed and angry at her and accused her many times of cheating on me. She told me over and over again that nothing happened, but I just could not believe her. She then became angry at me for accusing her of being a cheat so she decided that if I was going to call her a cheater she might as well be one. That is when she began her affair with my best friend.
Having failed to take ownership of the fact that her trip to the park was an act of cheating, she then decided that she wanted to cheat again, and used blame-shifting to justify her decision. You called her a cheat, so she would be one. That is just ridiculous, but it illustrates the way a wayward person's mind works.
Let's say there was some guy in town that you had a feud with, and several people knew about the bad blood between you. Then the guy gets knifed in an alleyway. No-one is ever caught for the killing, and although the police say it has all the hallmarks of a robbery gone wrong, your wife keeps saying that she thinks you did it, because you hated the guy. You protest your innocence, but she keeps on saying you did it. At what point do you think, "Okay, if she thinks I'm a killer, I may as well go out and kill somebody"? So you go out and kill her best friend. Does that sound like something a person would do? It's just ridiculous, but it is the thought process your wife says she went through in relation to your accusations of cheating, to justify her second episode of cheating.
The craziest thing about blame-shifting is that waywards are so short-sighted about it. They use it as an excuse, and to shift responsibility from them to their victim, but they fail to see that they are effectively saying they think and react like an insane person.
The affair lasted only a couple of months and she told me they only had sex twice.
Others have commented that this sounds like minimising, and it may well be. Two months and sex twice sounds weirdly 'balanced', and like a minimised way of saying "More than one month, and sex more than once". It also sounds very limited for an affair that your wife admits she embarked on deliberately to get back at you for not believing her story about 'nothing' happening in the park. Perhaps that was why she chose your best friend, but why do it more than once, but then stop after doing it twice? It doesn't add up.
And then there is the age-old tactic of simply lying:
It hurts to think that she has lied to me for all these years. I think back at all the times she has told me that I was the only man she has ever been with. I now know this is not true.
My reason for going through all of this is not to make you feel worse, and I apologise sincerely if any of it has. The purpose is to help you understand that your wife has subjected you to several techniques that waywards use to 'manage' the truth, which (a) confuse the betrayed spouse, and (b) make healing from an affair harder than it should be. That is why you find yourself in this forum, writing this:
I'm so confused and don't know what to do.
What I have written here is an attempt to help you understand where you are, what your wife has done, and why it has left you feeling confused and lost. My hope is that although it is painful (and all of us here have endured that pain), understanding the processes that your wife has put you through will help you to get a handle on them, to identify and see through them, and by doing so, to regain a sense of control of the situation. That may sound odd to you, but honestly, regaining a sense of control can be vital in the aftermath of discovering an affair.
You say that you are confused and that you don't know what to do, but you actually did a very wise thing in seeking out this forum and posting in it. I say that because there are plenty of people here who will want to help you. With more than sixty thousand members, there is a huge amount of real-life experience in the threads of the 'Surviving Infidelity' forums that you can draw on to increase your insight, and hopefully begin to figure out how you want to move forwards.
Speaking of moving forwards, you have not mentioned how the affair came to light. Was it a guilt-wracked confession after keeping it hidden for so long, or did it come to light in an argument? I am not prying here, but knowing how and why the affair was revealed can provide members here with insight about your wife's attitude to what she did, and whether she will be likely to do the work necessary to help you heal.
Another major thing that you must bear in mind is that you are under no pressure to make any decisions until you feel ready to do so. Take your time. You are very close to the discovery, and the common wisdom in these forums is that a person should not make a 'big' decision, like whether to reconcile or divorce, until six months have passed. If you need longer than that, take it. Remember what I said about regaining control? Giving yourself the time you need to make a decision is an element in taking back control of your life, so accept no deadlines other than the ones that you set.
It may be that what you want is a way to stay married, but get past this and ease the pain. That can be done, if the circumstances are right, and both people commit to doing the work that is necessary to make that happen.
There are several books available that can help to rebuild relationships after affairs, and regardless of the fact that this affair happened decades ago, its revelation means it is very fresh to you, and just as shocking as if it happened a month ago. So please do not think that being an 'old' incident means that you should not be upset about it. There is no statute of limitations on the pain that infidelity causes.
Speaking of the impact of infidelity, I hope that you are looking after yourself, and ensuring that you are eating regularly and keeping yourself hydrated. If you experience any physical side-effects, or things like an inability to think straight or depression, please go and see your doctor. These are very common side effects of infidelity being discovered, and doctors know how to treat them.
Another resource that you can try is individual counseling. The knee-jerk reaction to an affair coming to light is to go to marriage counselling, but the wisdom here is that it is better for both people, the wayward and the betrayed, to have some individual counseling to help them get their heads together before they get together to work on the relationship in marriage counselling.
If you do want to try individual counseling, do some research and try to find a counselor who specialises in infidelity. And do not buy into it if your counselor suggests that you are in some way responsible for the incidents of cheating. In this case it is clear that the park episode and the affair with your best friend occurred because your wife wanted them to, and made them happen, regardless of her attempts to blame-shift the affair onto you. I mention this because there are cases where bad counselors will try to turn the betrayed spouse into the villain of the peace, and that never works out well. So if you do try IC (individual counselling), find one that you get on with, and who does not try to blame you. If you find a 'bad' counselor, do not be afraid to move on to another one; it is your money, and you want something good for it.
Your wife really ought to have some IC too, to address her wayward mind-set, and to encourage her to be more honest. Her boundaries were, and may still be, very poor, and her thought processes and attitude to being honest are what are referred to in these forums as 'broken'. Cheating, lying, minimising, blame-shifting, and trickle-truthing are all indicators of a wayward mind-set, and if your wife has never had counseling or therapy to address that, she may still be exactly the same person that she was back then, which is why she needs to do the work needed to improve her values, honesty, and boundaries. If she does that work, and genuinely commits to it, it will help you to heal, because it will prove that she sees her old ways as something she sees as bad for her, you, and the relationship, and which she wants to change and improve.
I hope that at least some of this is useful to you, Seateasea. There is a lot more that can be said to expand on the things I have touched on here, particularly the resources that can help you, so please do post more, and also read the threads in this forum, and the other forums here.
Beyond all that, the most important thing that I want to say to you is that you have been heard. You have many brothers and sisters here who want to help you if we can.
Our thoughts and good wishes are with you.