Hey - I was in the same situation - not with a married guy though. He wasn't treating me right so I ended it with him, it hurt so much - I was pining over him for months. When I found out he was with another girl I accidently got back together with another of my ex's - big mistake. When I saw him with her I cried and cried inconsolalbly. It hurts like hell. When she screwed him over and he was at his lowest point he came back to me after realising how good I actually was for him. Some called me a fool for taking him back, but that was over a year ago and all my critics have been silenced by longevity.
However, if I had stayed in the relationship from the begining when he wasn't treating me right, I would have suffered and so would he, and I was prepared to never see him again, even though I was madly in love with him, I knew it was to right thing to do, something I had to do, even though it hurt. If he gets a divorce and comes for you, he's a keeper, and you'll have made the right decision as you have tested his words agasint his action. If not, then you've still made the right decision, as you'll know his true intentions.
Hang in there - and leave the ball in his court - and he has to back it up with actions remember. The ones you want - a divorce I assume? If he whisks you away somewhere or is real romantic, ignore him unitl he follows through. You've done the right thing, and you know this. :)