Reply #54: Don't tell her, but tell your friend

[realisticphish]

that he's a goddamn douchebag, and he needs to fix it. It is my belief that cheating (particularly a long-term affair) is absoluetly reprehensible. If he wanted to sleep with someone else, he should have split with her first, bottom line. I don't care if the marriage is rocky, a promise is a promise. What happens between them isn't your business, and telling the wife is far worse than getting him to tell her, but that doesn't mean you can't tell him what you think.