You can verify this yourself but my experience with Facebook is that FB routinely prompts me to be friends with: friends of my friends.
This is my experience too, but she swears he never "popped up" and she had never seen his FB profile before I searched him last week. It is hard to believe.
Also, you’ve assessed her current remorse level correctly, in my opinion. There is a nugget of remorse (she had nothing to gain by telling the truth, but did so anyway), but she truly doesn’t understand the impact of the betrayal (unfair in its own right) and continued lies about it (exponentially more unfair given you wound up married under false pretenses). You have every right to be furious with her because she, the person who was supposed to have your back, took away your ability to make an informed choice with your life. Her behavior is a deal breaker, period. In fact, it has forever altered the M that was/is. You simply must decide if you can attempt to build something new with her. She needs to show you she is worthy of that chance if you decide you can R. I don’t think she has yet.
I keep trying to remind myself of all the positives that are evidence of her being a different/better/remorseful person - she confessed willingly, she opened her accounts to me, she took and passed a poly, she has read many books and this forum, she writes me great emails and tries to do and say the right things.
I really try to make these facts my guiding light, but in the dark days I can only focus on the negatives - she slept with another man, she did it in repulsive ways, she manipulated me, she lied to me for my whole life, she kept the OM "close" by remaining friends with an affair enabler, she has lied to me even after D-Day and been deceptive, she continues to deflect and minimize.
R does not feel particularly close right now.
I note you said that the one lunch encounter, they went to an apartment. But it wasn't his, and it wasn't yours. Whose was it? Was somebody enabling/encouraging the A, or did the dude simply have a buddy who loaned him the keys like guys sometimes do?
Similarly, where were they when FB friend woman walked in on them? An apartment? A back room at a club?
The mystery apartment was likely the guy's best friend, who worked with them. However, my wife doesn't actually know. She just went with him and didn't ask questions. But, her first time with POSOM when she left the club, they were driven to the apartment by this best friend, so she assumes it was his. She assumes it was not OM's because he had a girlfriend and the apartment had no "female presence".
When they got walked in on, they were at a house party. No idea whose house. He followed her into a bedroom where everyone was storing purses/coats, and then they went into the bathroom for "privacy" to do the deed
As to the asshole, you mentioned he is married. Do you have any way of determining whether the woman he is married to is the woman he was dating back during the A? If you do talk to FB friend, and you are careful about how you ask those questions, you might find out. If it is the same woman, one step to consider would be to tell her about the A, and do it without informing your WW that you are going to do so. First, it would be the decent thing to do. Second, it might flush out very quickly whether there are communication channels still open from him to her.
He is not married I don't think. I mentioned that the FB friend/affair enabler seems to have a nice family. As to POSOM, his FB profile is just his face, and there are no pictures of kids or family to be seen.
The FB friend woman did not respond to me last night but did send my wife a "wave" emoji on FB messenger. I'm sure she is trying to determine if she should talk to me and how much she needs to lie. I responded from my wife's account (with my wife's permission) telling her it's OK to talk to me and tell the whole truth. Still waiting on anything more there.
You know what happens then. The FB algorithm recommends hundreds of friend connections, and typically people click "accept" without even really looking.
That's my wife's story, except the problem is that she did turn down quite a few friends in that early rush of adding new friends. She also admitted to me last night that part of why she accepted the request is because this woman had a crush on OM back then, and she felt bad for "stealing her man"
No only was she cheating on me, she was doing it with someone that one of her other (single) friends wanted to be with!
She thought of the friend request as some kind of peace offering from this woman letting bygones be bygones, and of course my wife loves to make herself feel good so she accepted it and was happy to feel better about what she had done. It makes me feel she had more remorse for this woman than she ever did for me, and it infuriates me. This woman then got a front row view of MY LIFE, and watched us get married, have kids, all while knowing what a monster my wife was back then.
By the way, the woman who walked in on them, is it possible that she was a vector in the A stopping? Did she possible confront your WW and say something like, "What the heck are you doing? What is wrong with you? You have a good man at home!"
No! Not at all! According to my wife, her response upon walking in on them was, "I wish OM would take me to the bathroom". And of course she was so un-bothered by the affair and my wife's actions that she friended her two years later once she joined FB, even though they completely fell out of touch in the meantime.
These people my wife were parting with were the types who work retail as a career. My wife worked there for six months, then got a better job, then a masters degree, etc. We are not anything like these people. Being FB friends with them is so incredibly inexcusable in my eyes because we are from different worlds and she would NEVER hang out with them again or want/need to see them again. Being FB friends, to me, was all about her people pleasing and being curious/wanting to flirt with danger in regards to the OM and keeping him just one step away. She swears this part isn't true, but it makes no sense to me otherwise. She was friends with at least three people on FB who would have been direct friends with OM, for the last 10 years.
Keep in mind that voluntary confessions like your WW's are rare, at least here on SI. They are especially rare long after the fact. Usually, those kinds of WS's take that to the grave. To me it reflects the fact that your WW has evolved and matured and, more than that, her direction has been toward a stronger love and higher regard for you. That, to me, is the big picture issue. She was once young, somewhat unstable, somewhat dependent on affirmation from others. She drank too much. She made horrible decisions. Over the years she has become somebody different, somebody better. Most important, she had come to hold your right to the truth higher than her own comfort or safety. That is something to both cherish and respect.
I know all this, and I do find things to love and respect and be proud of about it. But I just can't shake being so upset, and so hurt, and so heartbroken that she actually did what she did. I think she would be an A+ partner for someone else, where everything she did in the past could be boiled down to "I cheated, I was wild, I made bad decisions and was a bad person, but I learned and grew up and I'm not that person anymore." And for someone else, that would be believable and she really is a good person now. She could have a clean break and be the person she really wants to be and deserves to be seen as.
For someone else, she would be a beautiful, smart, caring person, a GOOD person, and a really excellent life partner.
But, because she did those things TO ME, or at least while committed to me, I just don't know if that life partner can be me anymore. It's too personal for me, too hurtful, and too difficult to accept or forgive. I just don't know if I can take it.