The most devious thing I can think of is to hire a woman to hit on this guy in front of your wife... to expose his lack of true commitment...
This is NOT a tested strategiy and is outright devious - its just something that I came up with in my head, but in serious cases where your wife's stability is in question and this guy is exposed to possible drugs and alcohol you may just have to get ruthless to expose these guys
Your wife will need to SEE this guy cheat on her and hurt her... to wake her up out of the fog I think
