Interesting about forgiving H as a co parent, but I think it is a step you can take because it doesn't involve you directly, you know? it's "for the boys" which is a step that lets your guard down a little. I think any reconciliation must be a process of tiny steps, because there is so much to look at and repair.
It makes perfect sense to me.
While my H doesn't have fantasy OW he does have MG, whom he texted and said if he had met her first he would have married her. Sometimes I get the feeling H is just biding time. So I understand the mourning process your H must be dealing with.