I wonder if he told your husband because he wanted to unburden himself or because he is hoping to get caught? That's awful for you and worse for your friend. I think telling her could bring on a whole bunch of difficulties, for you, for your friendship, and for her. She may already suspect. Is there a way to infer all wives should be vigilant - sort of an "I saw this thing on Oprah" kind of story - , so that she wouldn't know you knew, but could have her radar up? If you outright tell her and they work things out, and she stays with the bum she could feel uncomfortable around you. Good luck with it.