After all arent most women who are sexually assaulted assaulted by their husbands?
No. The vast majority of women have a husband who will ask before helping themselves to her body, or pause to ensure she's reciprocating before carrying on any further. A lot of men would be appalled if they hurt their wife.
Yours enjoys it. That's not a feminist, and it's not a man who doesn't understand or grasp the nuances of consent. He knows full well and that's what gets him off.
That's why we are so horrified for you.
In the 18 years DH and I have been together, there's not been a single time where there's been any ambiguity as to consent. And we've experimented as our relationship has progressed with more adventurous things but always have discussed it away from the bedroom first, and if it's something that one of us isn't keen on trying, it never happens. But if it is something that we are curious about, and both willing, even then, we would check with the other person first if they would like it in the moment before we go ahead.
It can take time to fully realise abusive behaviour. It took me several months to get my head around my ex being called abusive by women's aid and finally leave. And I think it took me even longer afterwards to realise all the other small things that were abusive. You can do this in small steps - please talk to womens' aid in secret and keep talking to them until you feel ready for the next step. The important thing is your safety and the safety of your children because abuse can become more violent if they sense you are trying to leave.
So for now, just make a phone call to Womens' Aid. Let them listen and let them give you their brilliant advice and support. And after that, you can consider your next step. But for now, just take that baby step.