[rcoreyus]

I think that people are responsible for their own morality, not the morality of others. That said, I think that this is likely to end badly for YOU. This sort of thing can't keep going on, but while it does it will get in the way of you having your own healthy relationship. It may also completely blow up in your face.

So, I won't fault your morals for having an affair with him, but I would fault your judgement.