thanks sinjin, I appreciate what you said to me about ML, believe me, I have questioned myself about it many times. It does come down to doing what I feel comfortable with, and although it may seem like I am letting him have his cake and eat it too, I think that it is having more of a positive effect for our R.

He tells me he feels bad after we ML, he says he feels bad for both me and the OW. I think it makes him question his feelings for both of us. He has admitted to me that he rarely ML with OW. It is more of an EA than a PA. I have asked him what he likes more about her than me, and he couldn't answer me. He said I am prettier than her, and way smarter than her. I know that she gave him a huge ego boost when he was vunerable and thinking that I didn't care enough about him. Now he knows the truth about my actions, or lack there of, but he is scared to come back...

I just have to give him time to decide what will make him happier - losing me and being with her or vice versa. He has told me before that either way he will be hurt. I guess he needs to figure out what would hurt more.
I don't intend to allow this double life to continue forever. But it has only been 4 months now, and although it is worse cause he has grown closer to her, we have also grown closer together at the same time. I will have to rethink my approach and strategy if nothing changes over the next month. I guess I am hoping that OW will get fed up with his lack of commitment to her and the fact that he no longer has any money to keep taking her out on expensive dinners etc.... (I am ASSuming this, but she is much younger and is quite the party girl from what I have learned about her).

Of course this would be wishful thinking. Most likely I will have to be the one to make a move, or him.