I may be wrong here, but I think you may need the space even more than he does. I even think you might be better off discontinuing the joint C and going to individual C. The tension with the situation and the nuttiness with OW make me think that you haven't detached even half as much as you need to.

Also, my intuition tells me that your husband needs to spend a lot more time at the "grass at the other side of the fence" before he can finally decide which side he really wants to be on.

And I think the more you try to make things "work," the longer itn may take for him to make this decision.

There is no arriving, ever. It is all a continual becoming.