Hello. I agree with a lot of what others have advised you. I have a good relationship with my parents but I have set boundaries with them as I can't handle expectations. I have a bipolar sister I had to cut out of my life because of her toxicity. I calmly explained to her that I couldn't handle her and how her behavior affects me.
Regardless if my boundaries hurt them or they don't understand doesn't bother me. It's about me surviving and not committing suicide. I've explained this to them and told them it had nothing to do with them, it was me and what I need.
I don't see anything wrong with you using only written communication with your mom or anyone else. Inform them this is the best method for you and it's what best for you which is what matters the most. Use emails, text or letters. We get caught up in the parent child relationship as adults and don't set boundaries with our parents mainly based on guilt and I have to do what my parents say but you don't and don't feel bad about it. Remind yourself, you are an adult now and it's about what you want and it's ok. It's your responsibility to take care of yourself. I love my parents but my complex ptsd and chronic major depression doesn't allow me to interact with them like I use to but I can't handle it.
It might be a good thing for you to write everyone you want to set boundaries with and explain what they do to you and what you are willing to give back and how. And remind them this is about you and what you need vs what they want or need from you. If they agree, perfect but if not, accept it and move forward as people's minds change often. Tell them in your letter to take the time they need to process and think about what you have said before they reply to you.
At some point too, you have to let go and be ok with it. Don't feel bad if you have to cut your mom out of your life.
Remember, it's all about you and your survival and no one is more dedicated to it than you. Take care of yourself, accept yourself, love yourself and be happy.
