Better to cut ties or keep fighting over boundaries?

My mother has autism. When she is frustrated with the world she picks on me. She usually starts with the big life choices - job, home, etc. But I like those, so if I don't get upse she moves on. My weight, my clothes/appearance, my volunteering. And if she hasn't made me visibly upset she starts in on how I'm not a good enough partner and my partner will leave me. 

Than, as soon as she feels better, she pretends she didn't say anything, or that I am too sensitive.  

I have spoken to her about boundaries. I say, I do not want to discuss this with you, or that's not your concern etc. I've tried talking when she's cheerful and she always agrees to boundaries, I've tried pointing out that's she's broken boundaries in the moment, and she says she doesnt care, she's my mother, the boundaries are ridiculous. I've tried discussing after things cool down, and she gets upset that I'm still upset. 

I've explained it's the pattern of disrespect that is the hardest, she says there's no pattern. 

Every time I see her, my mental health takes a dive. My therapist helps me prepare and helps me afterwards. But I can't socialise for weeks after seeing her. I'm too stressed. 

She is never going to understand, do I cut ties? Do I explain? Should I just never see her and lie on the phone?