I have been on "vacation" for a while but I just want to jump in here (haven't read all the replies so excuse me if I repeat something)...
I think the major thing you really need to answer for yourself BEFORE you can entertain the thought of working on the R with your H is this...bottom line...will you EVER be able to trust him again?...you really need to think about this because a R can't work unless trust can exist at some point. Yes, it has to be earned...but sometimes there is so much damage, so many broken promises, so many broken trusts that one just can't EVER trust that person again...and when that is truly the case it is best to take control, respect the memory of the 15 years you did have but let go of the heart felt hope of a future with him...
One thing I did learn from all of this is that if I had felt at all distrustful of my H and worried that he would do "it" (IT can be anything that breaks trust from just not loving you anymore to having an affair) again then I would have had to work on letting go of my one life dream of being married to my high school sweetheart and growing old with him...because without trust all my dreams would carry a black cloud that would not be fair to me...and it wouldn't be fair to him...
Now that being said...it is possible that right now you could say, "I honestly don't think I could ever trust H again." You could move on with your life (doesn't necessarily mean with someone else, cut the string, get the divorce and start living YOUR life for YOU...not for him...not for the dreams...not for the PAST 15 years...then who knows, down the road...H's actions start showing a different side of him...not one that just wants you because he doesn't want someone else to have you (think little kid with a toy that he doesn't want to play with but won't let another child enjoy it either)...he has his confidence, his morals, his own self in line and as friends you start making a connection...a NEW one....not one based on those 15 years...you could feel trust...and pick up and move forward with him...
I really think he needs to be let go...or pushed out...one or the other...because only then will he address his own issues...as long as he holds control over you with his emotions he won't ever grow from where he is...where he has been for the past 2 years...and I feel that the only reason he is not with OW is she got tired of the game that no one wins at...had she not moved on I think that whole drama would still be playing...
So...right now...in this moment with his actions as they are (you have assume that he won't change...you never marry someone with the idea of changing them, remember?)can you EVER trust him again?