What should I do my family life is horrible?

Okay so i am a 15 year old girl in 10th grade. My family is making me move from Maine to Texas this year. My father is a pothead and alcoholic who doesn't care about his own kids. All he cares about is my mom and his cat. He yells at me all the time making me feel like dirt and he blames me on everything. My mom just backs him on everything. My sister who is 12 is a bully and chases me around the house with a knife. So since i am moving i wont have my friends or family to help me when he is pissed off about something. I feel like a failure because of my dad. I have been wanting to ask this guy out for a while and i do not because i am afraid of rejection.