You are not alone in the length of the betrayal, or the details, and certainly not in the lack of knowing. Unfortunately, as you have been welcomed to the club already, you know that.
Them telling eachother they love eachother. Her telling him she can't lose him. Him telling her she's all he has. It's just so heartbreaking. And the whole time her husband and I there like two fools, not having any clue. They played it so well. Hardly even interacted in front of us.
Remember, in your head, to try to keep these things in context.
Many affairs are chock full of stuff like this, compliments, emotional gushings, etc.
It is all just so much bullshit, as people try to convince each other how special they are, how special their relationship is, and cover up the gaping wound they are tearing in their families.
Me, during my FWS affair, I get myself up in the morning, get ready for work, make my wife coffee, leave for work, work all day, come home, eat dinner, spend time with my wife and kids, and go to sleep, repeat the following day. I'm nothing special. Turns out the OBS was largely the same.
But, our WS's, oh, they were special.
FWS and her AP are throwing compliments at each other, fucking in the park, as well as each others homes, and other places, and talking up how wonderful each other is, while they actively work to destroy their families and to top it off her AP is trying to convince her to "run away together". It was all just crazy when looked at in a detached way. I mean, really, just how was that all supposed to work, the "running away", both families with small children, mortgages, car payments, etc?
The compliments, the talk, the behaviors, all just immature escape from reality, like pretending to be a superhero when you are a kid, but not doing your chores.
THIS PARAGRAPH BELOW, THIS IS IMPORTANT.
His contact with her was less and less over the last few years. I feel like this healing process is just never going to end which makes me feel like we will never work out. I will always have these thoughts in my head. Maybe if he was man enough to have admitted it all to me without me having to go look for proof then I l'd be able to get through it better but I had to read word for word their emails to eachother and it was gut wrenching. The hard part is how good we are together. We parent great together. We have fun together. Even now, on our good days, we have a great time together. Everyday he's thanking me for speaking to him and "allowing" him to be around me after all he did.
Sounds like he may have learned a lesson about life, about what really matters, and grown up somewhat. Now, he needs to grow up some more, and if he does, and works hard at it, you may have a FWS one day who is worth living with even though you can't completely get the betrayal out of your head.
It takes more than the talk though, he has to do the work to be a safe partner, he has to recognize the damage and UNDERSTAND the damage. None of that is easy work.
Good luck.