My whole life I remember her being a miserable person. She had a great life she just chose to be a . She has a lot of money and constantly thinks people are wanting to scam her. She hates her own mother. Her sister and her niece. She thinks they all after her money. She is cheap as hell. She wouldn't go out anywhere not to spend money. My whole life I have been her servant. After she led to my father's death with her nasty attitude, poor guy died of a heart attack. I am a straight up student in a medical school. I don't take anything from her. I take out student loans to pay. I have part time job to have pocket money. Everything I try to save up my mother takes because she believed I owe her. She considers me to the worst child in the world. I've never used drugs. I've never drank in my life. I did everything for her. When she went to nursing school I did all the papers for her, while struggling with my own school. She could get hysterical over anything. I mean start breaking things, yelling and blaming everyone. They recently raised our cable bill and I woke up to her screaming in my ear about what a I am. How lazy I am. How I never do anything and how I'm a bum. How I should be on the streets. One time she told me she wishes I was raped by someone and got killed. Sometimes I thought I was adopted but we look alike too much. Everyone hates my mom in our family. She had fights with everyone. She hasn't spoken to my grandma in forever and Se live together. I'm sick and tired of her. I am fed up with her I don't deserve this kind of treatment. And when I don't talk to her she becomes so nice all of a sudden. What should I do. I am twenty and I have long way ahead of me so moving out isn't a possibility

This sounds like my life, except that my father outlived my mother, much to the surprise of everyone, and I left home after high school.
I would suggest moving out by adding to your loan burden. None of my doctor friends had the luxury of living at home, and owed huge loans. Roommates to save on rent.
I dropped out of college and I wasn't even living at home, just because I was bitter about being at my mother's alma mater. (They gave me a full scholarship, so at 17 I felt I didn't have any choice).
You do make choices whether you think you do or not, and this is one you can do, and still stay in med school.

And just for the info. She has never been abused in her childhood. She was taken on vacations more often than I ever had in my life. She was raised like a princess with her sister. I am the only child

Not being abused, taken on vacations, and raised like a princess (which can be happy or miserable) doesn't mean she was loved. I would guess that she was terribly lacking in love.