I know I'm going sound like a skeptic, but here goes.
Is he hoping you will leave, so he can move on in and have complete control over your mom? He sounds like a real jerk. We've got 'em here in small town Texas, too.
I had to do the "enough" thing last night with Mr. dupre. He's been cranky and insulting lately and thinks he can go on and on with it (usually when he's in pain or tired). From the other room I said "Stop it." He usually follows this up with, "Well . . . " blah blah and so on, as if I had asked him to please further elucidate on his various insults. I kept saying, gently, "Stop it," right over his words until he did.
Then, when he realized I wasn't going to listen to any of it, he said he loved me and we laughed about it.
Menopause has its privileges.
It's sort of like a Lays potato chip. Once is NEVER "enough." You have to keep right on with it, with a rythm or like a chant right over their words. Probably not easy to do if you don't know when the next graphic episode is coming, but I know Mr. dupre's speaking pattern pretty well by now, so, anyway, it worked for me.
We've got a bully down here, too. And I just might post it to see what everyone's responses are. Like your bully, I can't entirely avoid him.