My cheating father

Hi Guys, I am from a Muslim family from Pakistan. I am 25 years old. I have seen violence since I was 3. My father would start beating by mother for absolutely no reason. We have always lived in a joint family system. My grandmother hates my mother. I have 6 uncles. Who are greedy and are liars. My parents are first cousins. Since my childhood my father has cheated on my mother again and again. We had to move to another city for my education and my father had to stay back because of the job. He has had 3 affairs in these 3 years since we have moved. My mother has tolerated everything as "Divorce" is looked down upon in our community. He never has time for me and my brothers who are younger than me. When he visits us (once a week), he is busy watching television and is constantly using his mobile. We cannot have a discussion on anything. I cannot talk to him, nor can my mother or any other family member, as he starts shouting and gets violent. We have "Eid" in our religion. Just like Christmas, its a day when family gathers and celebrates. Its after Ramadan. It was 2 days ago. 1 day before eid, He started shouting on my mother. He insulted her in every possible way. He commented on her age, height, appearance. My mother accidentally saw a text from someone, when my father left the phone in the car to buy something. It was from a married woman, who was buying him clothes for Eid. That was painful for my mother. She said nothing. Fast forwarding to the day before Eid. He insulted us and my mother. He cursed, he shouted like crazy. He said my mother was the reason he has health issues. He started cursing my mother's parents and brother who are dead. And then he said I dont want to live with you people anymore, and he left. It has been 3 days, he hasnt contacted us. My younger brother is very sensitive, I couldnt sleep last night because of this. He cried for hours. We spent our Eid, alone. Whereas, My father celebrated Eid, he visited his family members, His mother and other Relatives. The thing is that he doesnt know that we know about his new affair. He left 3 days ago. I spoke to my uncle who told me that my father visited them on Eid. Now the thing is that I am so done with all of this. I cannot bear this anymore. I cannot talk to him as he doesnt listen. My mother cant talk to him. We are all alone. Me, My mother and My brothers. My father's family is very happy that my father is doing this to us. My mother's family lives in America. We cannot talk to them. My father is a heart patient, so if my mother says, or asks, Why are you sad? Even such a small sentence triggers him, and he emotionally blackmails us that because of you people I am a heart patient. So the bottom line is that I cannot understand him a bit. He has ruined everything for us. My Mother cannot take divorce. I dont know how to fix this. His behavior fluctuates. sometimes he is the best father one can ever have. This lasts for a month. Then he becomes the father no one would ever want to have. I am sick and tired of this. Please help me.