How do you emotionally detach from a narcissistic mother?

I (18F) am finally fed up with my narcissistic mother and I need to find a way to emotionally detach from her. I don’t even know where to start or how to do it. We’ve been hip to hip ever since I was born, I was her first child of four, her oldest daughter. She has beaten me down emotionally and I can’t take it anymore. I moved away for college and our relationship improved, but being home for the holidays has made it exponentially worse. She claims I ruined Christmas because I gave her the slightest bit of attitude answering a question she already asked me a million times this week, claims I always do this. If I’m not the most upbeat, positive person all the time, then I have a huge attitude problem and need to learn respect. She says I’m an ungrateful brat if I ever indirectly suggest that she does anything wrong and that she isn’t perfect. When she says mean things to and about me that makes me cry, she refuses to apologize and says I should apologize for crying… and that is all only what’s happened since I’ve been home for break for two weeks. Growing up, I developed an ED due to her hypercritical opinion on my appearance that developed into a binge ED. When I was kid, she would force me to eat all of my food and said if I didn’t, she was going to ship me to a third world country. She was always my best friend one minute and my biggest critic the next. She thinks she is always in the right and that next to Jesus, she is the next perfect thing to exist. She always tells me I need to take more accountability, but she never takes accountability for her actions and how she hurts other people. Everything she doesn’t like about me, I learned from her. My supposed attitude problem? Came from her.

All that to say… how do you best recommend detaching from your narcissistic mother when you’re still her dependent?