I have thought that it may be good to limit visits to neutral places, such as having adjoining rental condos at a beach vacation. I don't want to cut my mother off, but her negativity and anxiety are only getting worse as she ages. (She is 70).
I think this is a good idea. It's important to set boundaries, as pps have mentioned, and this sounds like a good start. My mom wasn't anywhere near as controlling your mom but her behavior was similar. And I used to obsess about how she would be happier if she would only listen to me and go to Al-Anon. My dad had quit drinking 10 years before but Al-Anon would have helped her with her controlling, codependent behavior. I finally realized I had to accept that I couldn't change her. And then I told her I didn't want to hear anymore about how lousy my father was. That made her really mad but she stopped talking about him to me.
That was the beginning of a new relationship with my mother. Establishing that boundary helped me separate from her emotionally and eventually I could just relate to her as a nice person who was controlled by her anxiety. But I couldn't have compassion for her until I set boundaries. Take care of yourself first, OP, and then you may be able to have a better relationship with your mom - or not. But take care of yourself first.
You sound pretty self aware and like you're going in the right direction. Good luck!