I really need some help. Please read?

Well my mom has a boyfriend who is controlling, worthless, ignorant, manipulative, and possibly abusive but she will NOT kick him out. I can't stand him. He is an awful person. He has been gang involved. He has done HORRIBLE things in his life and is capable of murder. He has lied about going to work, drinking and driving in her car, leaving work, and she mysteriously ended up with a black eye but says she passed out and hit something. He follows her to the bathroom, she can't go to the store without him being VERY jealous. He gives my sister and I hateful looks, he has clearly expressed that he wants neither of us here. She is 13 and I am 16 and I graduated early and plan on attending college but my mom is keeping my car for him so I have no way back and forth to college. She says she'll get another car before August but I doubt it. I have some income so I can move in with a friend possibly but will still have no way to college but I am worried of how he'll become towards my sister and mom after I move out. So what do I do? Stay and deal with it and take a chance on the possibility of her getting a car? Move out? I am just so confused. Some answers of any kind are much appreciated