Does your IC treat your H? Does your IC know your H's head, heart, and guts? How can your IC make any judgment about what your H will and will not do?
What counts for me is this:
I would like the time and space away from him.
That's your gut communicating, IMO, and one's gut is usually pretty accurate (again, IMO).
The fact that you let his sadness, which may or may not be genuine, keep you from doing what you need to do is an issue, and I hope it's one that you and your IC are working on. His feelings are his to deal with.
The question you ask is: IC says separate. WH doesn't want to. What to do?
The answer is: Do what you think is best for you and your child.
If that means separate, well, your H just has to become an adult and remind himself that actions have consequences.
I know this is easier said than done. I have very little doubt, though, that doing what's best for you and your child will turn out to be best for your H and your M, too.