Yes, he is a controlling prick, and he will not like you having a life apart from him. This will not change magically at the point of settlement/divorce.
You are the one who has to break away, and imo, and from experience postponing it won't help you. Appeasement rarely does.
What can he do? Rant, rave, slag you off to DC. He can, and possibly is/will do that so don't factor him in to your decisions. I have said before, but in Scotland no one is interested in who does/said what and much greater emphasis on DC being in (one) secure place most of time. Finances too straightforward.
You have been controlled by him for years. He will want this to continue. It doesn't matter what you do or don't. he'll react anyhow. So let him now, or later. I'd go with now (and he may not anyhow).