Not one to post much at all...but unable to sleep in this hot weather, came across your thread and then read the first one too! I'm in tears, for you and also it brought back memories of the state of my relationship 7 years ago.
My WH also had an affair, but in our case, with a colleague who had been onto him like a rash for a very very long time. I'd pointed this out on more than one occasion, and she even went on to marry. Despite this, WH still went on to shag her for a couple of months.
We never really separated after I found out, but he moved out for a bit, and then in quick succession we lost close family members, which really tipped us to breaking point.
WH actually had a nervous breakdown nearly 2 years after my discovery, as he was just burying his head in the sand, refusing to acknowledge the hurt he'd caused and trying to railroad my emotions. It took his breakdown for him to 'sort' himself out, counselling, sorting out his work situation (OW was still at work for a while)
I wished I'd have the courage to have forced WH to move out, but I felt, like you do now, that leaving the kids was too much of a wrench. But I can see now that even they suffered for a while.
7 years on, he has reverted to being the man I knew since I was in my teens. Trust has returned which I honestly thought would ever happen. Your posts made me think back to those very dark few years.
It can be done, reconciliation that is. A couple of our closest friends didn't think so at the time, and unfortunately those friendships have been affected. But those who do understand are those who want the best for you, whatever you choose.
You sounded like you have a remarkable DB and even though they're his parents, the ILs seem supportive.
You have made some very wise decisions Tree, and only wished I had made a couple of those when I was in that surreal bubble.
I'm not saying that you & WH will get back together, but as long as you are looking after yourself & your little ones, I think you'll be OK!