What to do for an abusive father? (very long)?

Basically my father has abused both me, my mom, my grandma and when he was younger, my brother for as long as I can remember. When I was little I would get severe beatings and sometimes I would be forced to sleep outside. My dad would also threaten me on an almost daily basis that he was going to kick me out on the street and that I would be raped, tortured, killed, etc. and when I was younger he convinced me that he was my sole protector and the beatings were for my own good and that he loved me. He also tried to turn me into a homophobic, racist, religious zealot. Now that I'm older and I no longer take crap from him he doesn't try to get me to sleep in the yard or anything of that sorts but still spends the better part of our time together yelling at me and trying to convince me that I am worthless. He also has this control over my mother. My mom is usually very kind, forgiving, compassionate, etc. but if for whatever reason he gets angry at anything my mom even if she totally disagrees will start to mirror the outrage. He also yells at her all the time for the slightest things, for example if the large 5 course dinner she served him after working all the day was too hot, or if it is too cold, or if it is the perfect temperature that it tastes like crap. It has gotten so bad that she now has blood pressure and heart problems, all stress related. He used to occasionally beat her as well but now that I got older and could protect my mother he doesn't anymore to my knowledge. Furthermore he makes her take several buses to get to work (which is our tortilla bread shop) where she spends over 10 hours both cooking and working the cash register, all with no heat or air conditioning. On top of this she has to come home and do all the cooking and cleaning the house until it's spotless etc. while he spends his day sitting on his ***. I do as much work as I can and sometimes spend all nighters so that my mom can get some rest but I have school and I try to spend as little time home as possible, b/c of how bad my dad gets. And my mom has to give every penny she makes to my father and when I was younger and my bank account was still connected to my parents', he emptied out all my savings (11,200) and tried to get me to drop out of school so that I would work at the shop. Once I stood up to him and the fight got so bad my mom had a heart attack right there and he refused to let me call an ambulance and disconnected the phone. But then after a fight with him I got his cellphone and called the police and when they showed up he put all the blame on me saying that I yelled at my mom until she collapsed. My brother is also starting to act like him and b/c he strokes my dad's ego, my dad spends all the money my mom earns on him and doesn't make him do any work, even though he is 25. The worst part of this however is that my mom refuses to get the police or anyone involved. She also knows that he doesn't love her but she says she still can't leave him and once when I was about to call the police after my dad tried to throw my grandma (his mother) down the stairs my mom started crying and pleaded with me not to. Therefore I do not know what to do. I am convinced if I didn't live here my dad would have killed my mom and grandma along time ago. And no matter how much I try to talk with my dad and get him to change his attitude he just gets worse. Getting physical is also not an option b/c it would be me and against both my dad and my brother and my mom would probably get another heart attack out of it. So my main question is should I involve the police even though both my mom and grandma do not want them involved and if not what should I do?