What would have more impact is if you tell him that YOU lose respect for him being an adulteror.
I said that, too. Actually, I said both things. I told him that I had thought he was better than that.
The weird thing is, it may not seem to right away, but I've noticed stuff seems to sink in with him if I repeat it enough. I said "you're dating her" all this week, so now he will freely admit that. So, now I'm going to try variations on "you're having an affair," "you're screwing a married woman," etc., and see what happens... I have to just say it, and not make it sound like a discussion point in debate, tho.
