My WS had an affair about 2 years into our marriage as well, but I made ALL the mistakes that others have been warning your about. I believed it was somehow my fault, I thought that I could save our marriage, I thought that my WS had just made a mistake/that she was under the AP's spell, etc. In my case, we didn't get divorced, moved forward with having kids and the years together ended up exposing affair after affair. My point in telling you this is that while what you are experiencing is absolutely gut wrenching, you are being wise and are taking a path that will help you heal and avoid future pain.
Just to reinforce some key things, many of which others have already mentioned...
1. Your WH has a character gap deep inside. As a result, he pursued getting "ego kibbles" in an attempt to make himself feel better. On the outside, it may look like the AP has him under a spell or that he is on drugs, because he is pursuing the affair despite what it will do to his marriage, his family and, potentially, even his job. In effect, he is pursuing his next "high" over and over, but, the real issue lies deep within. One way to sum it up simply is that he is self-centered and unempathetic pursuing only what he wants. Until he comes to a point of realizing the problem is within AND wants to do something about it, he will remain a self-centered person who is an unsafe partner for anyone.
2. Seeing one's faults and taking responsibility is a very difficult thing. Some people avoid doing so their entire lives. Your WH doesn't want to take responsibility and, as a result, will do anything and everything to avoid seeing that he is being a self-centered, manipulative, destructive cheater. That is why he has tried to rewrite the history of your relationship, why he is trying to blame you for everything and why he doesn't want the news of his affair to get out.
3. You can't fix him. Only he can do that.
4. The insidious lies that many betrayed spouses believe are (1) that the affair was somehow their fault in some way and (2) that they weren't good enough/worthwhile. I can't say this strongly enough -- the affair was NOT your fault in ANY way.
5. Step back to let your head clear a bit. The FAQ for Betrayed Spouses can help, especially the 180 (https://www.survivinginfidelity.com/faq_bs.asp#FAQ11). The truth is that your WH is currently emotionally, psychologically and financially abusing you. Being able to see that will help you in choosing your words and actions wisely.
From a practical standpoint, what I'd suggest is...
- Let your lawyer advise and handle things for you. Your WH has effectively kicked you out of the house and cut you off from any ties to it. While the home might be in his name, you are still married and that gives you certain rights.
- Since divorce appears inevitable, take your lawyer's advice about exposing the affair, especially at work -- loss of his job could have an impact on your divorce settlement. Once things are finalized, you are free to allow consequences to occur by letting out some information if you wish.
- You've grown to love his family and there is no reason to sever those relationships just because he is trying to avoid exposure and responsibility. All they need to know that that he has asked for a divorce and wants you to cut all ties with his family, but that you wanted them to know that you love them and would like to continue the relationship if they are willing.
- The fact that his family is trying to point out the destructive path he is on is called love. The uncomfortable feeling he gets due to that is called consequences. Don't let his lies tell you otherwise.
- If you also choose to share with his family that the divorce is due to him pursuing the OW, that is your choice, but you'll need to think through whether you then need to tell them about how the information getting to his work could be detrimental to you and consider whether you can trust them to (1) not mess things up or (2) not mention it to him.
- As far as his "best friend" goes, he sounds like a real weasel both from the likelihood that he knew about the affair and that he now is trying to take advantage of your pain to make a pass at you. While the information he has been funneling you is likely insightful, you'll want to seriously consider putting some distance there or end the relationship altogether.
- Finally (and most importantly), take care of yourself. You are going through an enormous emotional trauma. If that was a physical trauma, you'd be in the ICU right now. It is really, really important to find your own emotional ICU -- family, friends, counsellors and even this site -- to help you grapple with the grief over losing the marriage and future you dreamed that you'd have along with dealing with the betrayal, manipulation and outright assault that your WH is subjecting yourself to.
I'm so sorry that you are here, but I'm glad you found us. Feel free to vent, ask questions or seek encouragement as part of the long healing path that lies in front of you.