Shall I move away from my mum?

Im 20years old,I live at home,I moved out for the second year of uni because things got too stressful at home.I failed my second year because I’ve just realised im studying something that I dont enjoy anymore,and im kinda doing for my mum not me anymore. Since moving back home my mums been really horrible.she doesnt let me go out or even have friends.she says im fat, a whore,lazy and that if she was me she would starve herself.im a size 12/14.I dont think im fat.well thats what people tell me.she says im stupid and that I will never go far in life because im dumb,eventhough I got good enough grades to b studying law that I only studied because she made me.im planning to just leave without telling her because I know shel beat me up and lock me up if she knew.im planning to move with my boyfriend to america.im planning to work and save up enough to tie me over until I find a job over ther,and mayb consider doing uni over there when im ready.my boyfriend is behind me 100%.am I over-reacting by moving away and living my life the way I want?or should I just take it and stay?