As tough as it will be for your H to move out (if he does), what is your plan for visitation? I used to work on the day H comes to visit D's (yes, he comes here to do that), then I would just be out some, now, mostly I'm home. I let them take care of dinner and sometimes they go out for a bit. My D's have only stayed with him 2 x's each since he left.
A distinction I have become really comfortable with is that it's "our" house, but "my" home. I don't leave or put myself out b/c he comes here to visit.
No matter how prepared they are, it's still tough on the kids. My D17 has never really said anything about it. When we told them her words were that she wasn't worried b/c "I know you guys". It's that she's kept closed off that continues to worry me. 2 of her closest friends have told me (no, I didn't ask) that she has never spoken to them about it. I have learned to watch and listen with more than my ears.
If he is set on leaving, I don't know that I would let him know about future DB sessions. As an aside, my H and I use my DB coach (he doesn't know about DB that I'm aware of) to help us communicate about the kids and parent better. B/c of where he lives it's easier to schedule a conference call to do this. So far, it's worked pretty well. I'd be happy to provide more details if you contact me on the alt.
That he still waffles, well, just get some syrup out