Divorce from Abusive Husband and father

I have an alchoholic father who abuses my mother and me both mentally and physically, he has various extra marital affairs and he had literally made our life living hell. As he is the only income source in the family we are dependant on him & he always reminds us about this through his abusive language and death threats. He has a good secured government job in a bank and is on a respectable designation. Yet he doesnt seem to care about anything at all. He doesnt see us as family he calls us parasites, he doesnt like us at all. We are a higher middle class family but now its hard to sustain as he torture us right and left before giving monthly allowance. I am 21 years old college student and it will take 3 years for me to complete my studies. My mother and father has been married for 20 years and she is a housewife who has tolerated his physical abuses right from the first day of the marriage. My question is we want to get seperate from him but as he is the only one in the family who earns, even if i start a part time job i wont be able to earn as much that i can afford my studies and sustain myself and my mother. So is there a way we can get separate from him and get him to continue to pay us monthly allowance that he does now and support my studies ?