KGirl, ignore the fact there is an OW. She's not the reason your M is where it is. As you said, she is a symptom.
One of my male friends likened it to this: we all walk a bridge in life from one point to the next. The M bridge started to crumble, and OW was in a lifeboat waiting to give him some support if he fell. Eventually he'll want back on some solid footing. So we gotta rebuild some bridges to make them stronger so nobody needs that lifeboat.
Even if you and H end up on different bridges, make yours strong enough to last.
My IC and DB coach also said to disregard OW-she is not the problem and giving her time and energy is taking it from an area that deserves it.
Me: 39 H: 45 Second marriage for both H left 12/2013 M:4 T:5.5