I should probably answer those of you who think I went easy on the guy. Because of my "background" and previous profession, my wife had already warned him that I'd easily take him down and possibly kill him if I want to - I did warn him when I spoke to him that too and I could actually hear he was scared sh**less and he said yes, both he and my WW said that my WW had warned him it was a real possibility - it was at that point he started swearing NC. In reality, he's not worth going to jail for of course.... but He doesn't know that. Despite the drama I had to suppress a smile when I heard the quiver in his voice and frantic apologizing.
I beat up my fWW's boyfriend and all I got from it was a night in jail and a misdemeanor assault on my permanent record. You did the right thing holding back. Believe me, beating the hell out of the guy would not have solved anything and you would NOT feel any better.
The reason you would not feel any better is because the real scoundrel here is that faithless wife you are married to. She's the one who deserves the brunt of your rage. The OM was just a random punk your WW chose to have an affair with. Had it not been him it would have been someone else. Your WW did this. The OM was just the vehicle she used to do it.
As for telling his W, I'm not interested as long as he stays NC. I think he's more scared of me killing him than he is his W!
Lame. This woman may be living a lie and you would be allowing her to live that lie and be unknowingly taken advantage of by her worthless POS husband. I think you have a moral obligation here to tell her.
So to answer some of the other questions, my WW confessed to me unprompted and said she could not take the guilt, and that's why she was telling me.
Bullcookies. She was afraid the OM or someone who knew of the affair was getting ready to rat her out. She needed to control the narrative in order to reduce the damage, so she told you. I can guarantee you got the watered-down version of events.
Now I see some folks have said they don't accept the psychology of how an affair can start - well absolutely, a person is not forced to drop their panties, but the classic of one person feeling unloved confiding in another who exploits it is an old, old story which I've seen before myself.
There are thousands of unhappy married people who feel unloved in their marriages who don't have affairs. Your WW had an affair because she has crap for personal boundaries and a broken compass.