I know you know his behavior is unacceptable, and you've made that clear to him. Does he also think it is unacceptable, or merely that you don't like it and therefore he will reluctantly work on it to keep you happy? I feel like that is a kind of important distinction. If he doesn't want to be a mean person but does it sometimes and needs help in addressing his insecurities or whatever is at the root of that behavior-- and is willing to do the work in altering his responses to certain triggers, that is one thing-- but if he doesn't really think it is all that big of a deal and is just humoring you, that feels far more serious and unfixable.
That whole episode must have been awful and I'm sending you a virtual hug. It especially feels raw in that I think three or four months ago, had he done this, you would have rolled your eyes and walked out of the room. But you're opening yourself back up to him, and he's been so much kinder and it seemed like he'd left this side of him behind-- it really had to be hard to have it all come back out when you're more emotionally vulnerable than you were before.
How are you feeling about all of this a few days later?
Me (46) H (42) M:14 T:18, D9 & D11 4/19 - 12/19: series of escalating BDs 9/20 - present: R and piecing