Is this sexual assault?

A little backstory. My partner has sexually assaulted me before, he said he didn’t think I meant it when I said “no” and “stop” and he’d beg me for sex until I gave in. Our relationship has been platonic for around a year now due to this and a previous sexual assault that I am in therapy for just now. He knows not to touch me sexually, we have discussed this thoroughly and how It makes me feel - like I’m being violated all over again. Last night I didn’t have my medication so I couldn’t sleep, it was 4am and I was just feeling exhausted and overstimulated so I took my bottoms off and slept in my underwear. Only to wake up a few hours later with him caressing my thigh and ass. I sleepily pulled away and he stopped. It happen twice more until it really woke me up and I yelled “stop” and he did. In the morning I pulled him up on it. Telling him he knows I can’t be touched like that right now and that just because I sleep in my underwear in MY bed doesn’t make him entitled to touch me. He said I was just teasing him DUDE I WAS FUCKING SLEEPING!!! He blamed me for it. I know he was wrong, he knows he was wrong. But is this classed as sexual assault? He didn’t touch my genitalia (that I know of anyway) just my legs/thighs & ass.

[EDIT - I want to remain anonymous incase friends/family come across this]

Leaving him doesn’t feel like an option. We’ve been together nearly 7 years, have a child and home together. The thing is he’s my first real relationship, I didn’t know a lot of things weren’t normal until fairly recently.