I Have Family Members That Get On My Nerves

My father has a number of health issues and he doesn't take care of himself at all. He recently had all 5 toes on his right foot amputated and he's still making the choice to smoke 2+ packs of cigarettes every day and eat whatever he wants even though he's a diabetic, and his main arteries are completely clogged from his feet up to his waist. He's extremely verbally abusive to my mother and the only reason she hasn't left him yet is because she trying to save up enough money to leave. My brother has autism and he's nonverbal so someone will always have to take care of him, and my mom wants to make sure she has enough saved up to be able to take care of both of them.
My father has been a complete nightmare to deal with since he has returned home from being home in the hospital for 2 months. He screams and curses at almost everyone when they say something he doesn't like. He my mother "she's retarded just like her son". I have to work very hard to not punch him in the face or just flat out curse at him and call him everything under the sun. He has some people outside of the immediate household fooled into believing that my mother is a horrible person who doesn't care anything about him and that she doesn't take care of him. Some people has started treating her coldly as a result of his lies. Even after years and years of knowing that my father lies and manipulates, it still shocks me how he continues to be an awful human being even with everything going on with him and his health.