Did anyone call the police when he abused you? Did you tell anyone?
No you have not been living with your mother by your choice. It’s by your parents’ choice. Now your dad has custody and if he was so abusive I find it hard to believe they would just give him full custody over your mom. You don’t get to decide which parent you live with. Yes your mom could have gone to jail for you not going to live with your dad.
Again it’s pretty odd him being so abusive your mom didn’t get any custody of you. Yet she got joint with your sister? You apparently don’t know what is going on because you are missing huge chunks of the story as others have stated.
You need to read the stickied threads about emancipation. No you can’t get emancipated. How are you going to take care of yourself?
I think there’s a lot more to this story than has been posted. When you are the legal age of majority in your state you can do whatever you want. You can live where you want. You can see who you want and so on. Until then you live with your father.
If he’s abusive you need to call the police or tell a teacher or a counselor at school.

