Last weekend I found out the girl I was seeing was having an emotional (possibly physical) affair with a married man. We weren't exclusive but he was calling her and texting her non stop all weekend. I confronted her about it, she said it was just a married friend who needed help. I could tell by the way she talked on the phone with him that it was more than that. I asked her again, saying I didn't care what she was doing when she wasn't with me but that she should probably stay away from married guys and that she shouldn't lie to me. She insisted it was just a friend.
I snooped her phone while she was in the shower. Clearly more than a friend. I confronted her about it, told her to take care of it by the time I got back from work. She did what I asked but later I couldn't help myself and checked her phone again just to make sure. She caught me checking that time, got really pissed. We fought, made up, and things seemed ok. Then 5 days later she sends me an email saying that our trust issues are too big and we'll never be able to get over it.
A few questions:
Should I just let this be over? It was semi long distance (she's in my town about 25% of her time). I can see her again in a few weeks and can probably patch things up in person (our chemistry is insane).
I have the OMs contact info and through that got his wife's info. They have a 2 year old daughter. Should I do anything with this? One thought I had was to send the guy an anonymous note pointing him to this site and telling him to get some help before he fucks up his family. The less healthy thought was to just send an email straight to his wife with all of the info about what's been going on and let her figure it out.