how do i tell my family i don't want to live with them?

this post is going to be a bit of a trainwreck, so bare with me. i've already rewritten it once.

i can't be myself at home. my family is homophobic - not really violently or intensely, i admit, but they all hold that "they're different from us and we don't want them near us" mentality. there's also some emotional abuse going on from my mom and my sister - i.e. i got told i was ruining my mom's marriage and being selfish when i asked her not to take me skiing, since the last time i went skiing i had to get stitches.

the only person who doesn't hold the homophobic mentality, funnily enough, is the person who scares me the most. my older sister is eighteen and just went to college. she and i are on good enough terms because i'm too afraid to ever cross her. she's a drug addict and has told me before that she doesn't feel guilt.

she threatens to kill our family members, she's robbed stores, she's pretty abusive emotionally and manipulative, (once she sobbed on the phone to my mother while driving me to school, then she wiped the fake tears out and said "that's how you manipulate people."), she calls me useless/worthless/good for nothing for things as little as getting her order wrong. i haven't crossed her out of fear so she isn't really that mad at me, but i know that i'm going to fuck up and she's going to flip and i don't feel safe. i always feel like i'm living on edge.

granted, she's at college, so she's not here most of the time. however she has my mother around her finger so whenever she wants to come home, she can. she's coming home in two weeks time for a week, and honestly whenever she's home time just drags on. i feel like she'll never leave.

my dad and step-mom live out of state, and they've disowned her after she stole some thousands of dollars from them. after a particularly shitty week, they told me that if i wanted to move in with them, i could. it would be completely different from anything i've ever done before, from anywhere that i've ever lived before. however, i'm actually here for my february break right now and it's so peaceful compared to home. they're both so open-minded about my sexuality. it's not even a factor.

i know i should move but i don't know how to tell my mom without her getting mad, and there's honestly something holding me back. i know it's not going to be heaven there, but i think there's no way it can be worse than this. i tried to think of some nice things about home to even the playing field but honestly i don't think i can. no one's home most of the time and when they are, it's just yelling.

thanks for reading, and sorry it went on so long.