I know already without reading replies that there's probably some controversy here. But I'm going to hold my breath and give my two cents because actually, my bf was married when we first got together and I'm not here to bash you but I'm going to speak from my experience. The marriage was pretty much over when I came along. She was using drugs, they slept i separate rooms, no sex for over a year, and both were seeking other people. But to be honest, that's no excuse for me butting in and being the straw that broke the camels back. Not to mention the huge amount of guilt I felt. I still cry because I feel so bad for his ex. And now every time we fight I think about how he cheated on the mother of his children and wonder what he's capable of doing to me. I've been called every name in the book because of it. Nails in my tires, threats from her and her family, and he had to carry mace on him! After the divorce was final and her and I got into yet another argument, I broke down and said how incredibly sorry I felt. And on a good note, her and I get along now for the kids sake. But I know deep down she still probably wants to push me off a cliff and rightfully so. Just a few weeks ago I called my dad crying because my bf and I got into yet another blowout and you know what my own dad said to me!!?? ..."that's what you get for coming between a married couple!" So yea, I don't know your details or his and his wife's relationship but no matter how bad it may be, wait till the divorce or a legal separation is final. Don't get me wrong, I love my bf and his kids to death but I really set myself up for a bad situation. And most of all, if he's capable of being unfaithful to his wife then what you are to him now or in the future is no different. Hope I helped some!!

Edit: just a thought... you may want to work with your counselor on WHY you're attracted to unavailable men. There may be a underlying issue with your own self here. Maybe you like the idea of someone actually leaving a marriage for you or maybe that's not it at all. Question is, what if he was single? Would you still want to be with him that badly? In my case there is an issue within myself that makes me want unavailable men and their attention but I'm not here to talk about my issues.