I feel sorry for my dad

My dad is abusive towards me, my mom and my small brother.
When I was small, he used to beat my mom in front of me, and I was so useless that I was never able to do anything to stop him. He often explodes with anger for no reason at all, when I am around him, I need to always watch out for how his face is, how is his tone of voice and other gestures to judge whether he is getting angry or not. He once threw TV on my mom.
We live in a city far away from our hometown, we don't have any relatives around. He doesn't like us talking with our Neighbours also, due to his actions, most of our Neighbours try to avoid us. In our hometown, my dad is the main earning person, so even if we tell our grandparents about him, they never oppose him.
My mom always said that everything is fine, at least you will be able to stand on your own legs after your education, even I thought after my education I will take my family away from him but from past two years he has started using this against us. He often threatens me that he will stop paying my college fees and my brothers school fees. Everytime before a week of paying fees, he starts getting angry and finds reason to start fight because he knows we cannot oppose him due to fees. He feels threatened that once I get a job, he won't be able to rule around on anyone. He also says that I owe him for raising me. Once he stopped buying fruits and vegetables for entire month, we had to somehow manage with rice only, he bought that rice only so that we can't say that he is not even giving us food. He gives me pocket money, but if he often tells me to give that money back - he makes excuses like why you need money, I will give you back later, I don't have cash on me right now etc.

Now, I was trying to study but he created a new issue and how much ever I try, I am still getting little distracted that's why instead of crying or burning with anger this time, I simply decided to type this post. There are more 3 years to finish my college, and this is India, even PhD holders roam jobless here, so don't even talk about trying to find a part time job.
I no longer care about getting few kicks from him, I have long ago learnt to ignore pain, but I don't know how to protect my mom and my brother. Just after last fight between my parents, my mom tried to commit suicide by eating too many paracetamol pills. Later on, she failed because she vomited most of the pills just after two to three hours consuming them, and I literally don't know whether I should be happy that she was saved or sad because she still can't leave this hell. Earlier I thought I can end this, after getting a job. But the condition is getting worse. It was not more than 2 years when he got retired and started living 24/7 with us, that I understood that his anger issues is not normal, before that he had to go for work or was posted on some other regions, I felt little sad but never thought that my dad is insane, but now I simply think that it is all his fault. He says that he doesn't have money to raise us, but still he dared to marry someone, only to make her life hell, and even dared to make her pregnant only so that he can further bind her. My mom once told me that she often thought of committing suicide but never did that because we were too small at that time.
I know I need to somehow endure this for more 3 years, this is the final moment, after spending more than 12 years in hell, I can't do something stupid now, but I can't see my mom like this anymore.

The thing is when I try to find bad traits about him, I can write entire documentary on that, the more I think the more I find bad about him, but on flip side when I think about what is good in him, I must also say that he is not completely bad, he just want us to be completely dependent on him, and I think he kind of likes to blame all his problems on someone. I think he doesn't know anything about meditation or spirituality because I found that whenever he is left alone without any work, out of habit he starts to think something bad, or something which makes him angry, he just can't keep his mind quiet. To me, he appears like a patient who is struggling with his feelings and emotions. Money is just an amplifier, if you are good, it will amplify your good character and give you more power to do good, on the other side if you are bad, money allows you to do more horrible things that were not possible before, it can turn you in to monster. I think he doesn't even know how much wrong he is. I could have directly talked with him, but the risk is that he is the one earning right now, anything I say, he will only reply with "Do that when you start earning, this is my life, and I will do whatever I want", he also drinks a lot. It is always better if I can keep his mind filled with something, so that he doesn't have time to get angry even on holidays, I can engage him on some movies or series. On working days, he is mostly busy with stock market, his mood also gets little effected with how the market performed on that day. And from what I can guess in his point of view, we are the ones causing him trouble, he definitely has very bad children and a horrible wife, his life is ruined because of us, and whatever he does, he can't get rid of us. He is always trying to run away from his responsibilities. He never apologized after beating someone. But he doesn't know that the family, neighbors or the world is not the problem, the main problem is his own emotions which are running wild.

I don't understand how my grandparents raised him, he doesn't have a single ounce of feeling for others, and the best part is he is suffering because of it, how much ever he hurt others, he is never satisfied, how much ever money or property he gets, he always wants more, he controls our lives, but he still want to make us more dependent and beg him but he is still not happy, he is a living example of happiness never comes from selfishness. I started this post filled with anger towards him, but I can't help but sympathize with him at last for having such a miserable life and always being trapped inside his mind, which when left alone always makes him more miserable. Even if we die, he will find someone else to blame, today we are his problem, tomorrow it will be someone else. May gods bless him. Just because I am in this situation, I won't allow any outsider to fill my mind with hatred, anger or other negative thoughts.
I just need to hold on little longer. 3 years until I get out of college. I am also trying to get internship somewhere. After that, I will definitely shift to somewhere else, and will never take a single penny from him, I will also pay take my brother and my mother with me. I will allow him to live for a year or two alone, so that he realizes that we were never the problem, after that maybe I can talk with him. At the end of day, how much ever he is wrong, but he still had raised me up, I just cant leave him alone in his old age.
Whatever, my today's study time is over, and I have definitely calmed down a little. I don't know why typed this useless post, but even if I have calmed down, it will be a waste to simply delete it.