Not quite sure if this is a question but perhaps maybe this should be a sticky, because it is a really good statement for people who are horsing around with married people.

So why keep doing what makes you feel bad? Explain that to me, as I don't understand it.

Resolve to move on and you shall. It's a no win situation and many people stand to get hurt if not in fact devastated. Sucks, I know but drop all contact, make a list of why he's no good (trust me you'll find many reasons) and stay busy doing things you really love to do.

I think its an answer. Don't cheat.