I think, from what I've heard, his relationship with OW is over. I don't know though. That's an idea. I just don't get why all of sudden he is fixated on it
Regarding MC, IMO, his commitment to working on the M is more important than if the OW is out of the picture. Your posts have indicated that he didn't end the A, she did. He has yet to show you any action that indicates he wants to work on the M. I agree with Toots. It's perfectly alright to tell him you are not interested in going to MC if he is not willing to work on the M.
Me: 30 H: 35 M: 5 years S2 Signs of MLC started Feb 2014 BD - PA July 2014 Piecing/reconciling late July 2014