First of all, I agree that KARMA will come back to haunt you in a bad way. I was involved with a married man and was the OTHER woman, too, and I think I am paying for it dearly now in my own marriage. I am married, and my sex life with my husband SUCKS. We have been married for what will be 4 years next month, and we barely have sex and are now having marital problems around this. Can't be nothing else but karma.
Second, I also agree that you shouldn't have gotten involved with a guy whom you knew was married in the first place, and RIGHT NOW, you need to separate yourself from this loser, find an UNATTACHED, AVAILABLE man and get on with your life!