Domestic violence and man handling of family members and threats

Hello Sir/Ma'am, I am a student of Engineering and wish to ask a few questions upon my case as i really find the need to act legally. I am 19 years old and I have a younger brother of age 15, me my brother and my mother have been bearing mental and physical torture from past 20 dreadful years my parents haven't gotten a divorce but have a semi-divorce condition where she stays right next door with her parents and we kids keep shuffling day in and day out from one flat to another. this case is of very serious tone let me put clear before it is foreseen as a regular domestic violence case. we kept our mouths shut all the time for the past two decades but due to my father being a raging alcoholic and has no absolute civic sense and uses all sorts of shouting beating and harassment techniques on us and has made our lives miserable. I study in a different city now due to college but my brother and mother are still undergoing this non-sense. From the time my grandmother(maternal) had a hip replacement surgery due to a broken hip which my father had caused in a utter family dispute my mother has totally lost hope in him and left him to her mothers place. But that didn't solve anything the disputes raged more and more and the condition has started to get severe day by day, we have bruises all over our body, neck and go to school in embarrassment. lately we children have started to retort and stay put and tell him to stop this and live peaceful but that ain't happening and he is blackmailing us that he would stop paying for our school/college fee's and leave us to the roads. I know my fathers mentality he will do it, as a matter of fact thats why i am asking this question. he also has a drunken driving case already on him, he has stabbed my mother with a knife many times fortunately we were there to rush her to the clinic right away. to be very blunt he is a maniac loosing his mind to alcohol and frustration. We don't want to spoil our future in this mans alcoholism and screw up our careers. the property has been given in a will to my father in the most legal way possible, it is rightfully his but as his sons we do have a right on it but he says he will abandon us. i want to take an action on him, what can i do? please suggest me.