As-salamu alaykum - I don’t get why people let husbands abuse their wives and do nothing

Long post, sorry. As-salamu alaykum. Feel free to look at my older posts if you want, but anyway - I’ve been depressed for a very long time and a big reason is my family. My mom isn’t mentally well; I’ve had many problems with her growing up. I’m 23 now and still have to remind myself she isn’t all there. I have three siblings: a little sister who is developmentally delayed, very childish and undisciplined - she’s 18 but has the kindness of an 8-year-old; a 30-year-old brother who is narcissistic, rude, hypocritical and has drifted away from Islam and morals; and my older sister, who’s the only one who seems normal and has more morals than the rest. My dad has failed as a father. He’s really drifted from Islam - he even doubts Allah sometimes - and no wonder my brother turned out like he did; I don’t think my brother even believes in a Creator anymore. My dad affected me deeply and I don’t think I’ll ever fully recover emotionally from what he did and still does. As I’ve gotten older and started caring more about morals, it’s hurt more. I’ve been in therapy since February and on antidepressants since July. My dad has abused my mom throughout their marriage. They married 31 years ago. He verbally abuses her to this day and he physically abused her too - at one point she was hospitalized, she still has a permanent scar on her forehead, and he even went to jail once. He did this in front of my brother and also beat my brother horribly when he was young. He hit me and my other siblings too, though not to the same degree; a spanking or a stern talking-to would have been fine sometimes, but the severe beatings were too much. There are things I can’t unsee. When I was a kid and tried to protect my mom from his yelling, he threw something meant for her but it hit my head. Another time he struck my mom with a framed Quran portrait hanging on the wall and broke it on her head - her scream still haunts me. He’s so far from Islam that he even swears at Allah in Arabic and curses us in Arabic. He calls my mom every disgusting name. He shows no regret or remorse, is stubborn, thinks he’s always right, won’t take criticism, is judgmental and cruel. There were some good moments and times he did right - he likes to think paying the bills makes him the best dad - and I promised to take care of him when he’s older. I’ve tried to be a good son and don’t argue much with him. Recently we had a big argument. My little sister got detention for oversleeping and being irresponsible. My dad told me to pick her up and not bother her, but I asked her why she had detention and told her she needs to stop these habits or her life will get harder. I gave her an older-sibling talk because our parents don’t parent her. She started crying when we got home, and my dad called me twice, got angry, swore at me and at Allah, called me names, and even threatened to cut off my school payment. The things he said in Arabic were the last straw, so I snapped and yelled back. He tried to intimidate me but realized I’m not a child anymore. He practically kicked me out. My mom cried and begged me to come back, and I’ve been ignoring my dad since. I don’t understand why my mom stayed with him. I think it would be better to face financial struggle than live with that emotional abuse. I’m almost certain my dad didn’t want kids - when he got mad he used to say messed up things, even wishing we were dead or telling me to kill myself. He doesn’t seem to realize how much he’s made my mom worse over the years. She wasn’t fully well mentally before, but he made things far worse during these 30 years. What disappoints me is that my aunts and uncles have let this happen for decades. According to my mom they tried talking to him and had interventions, but he only stops for a week at most. Sometimes an aunt would come when they fought and my mom would tell her about the abuse, and the aunt would tell her to be patient in marriage. I don’t understand how my mom’s siblings allowed this to continue while their sister was being hurt and nearly killed several times. I’m so angry at my dad and almost my whole extended family. My mom never had a normal life from childhood and then these 30 years of abuse - she got used to it and never divorced him. Sadly, this happens a lot in our culture; relatives want problems to blow over and then ignore them. Me and my siblings nearly felt hopeless enough to harm ourselves when we were younger. My older sister, who is married, still has trauma and can’t visit because my dad bullies her. I’ve given up hope on my dad. He has no morals and tries to take advantage of Allah’s mercy. He had a tumor and cancer years ago and for the first time in decades he prayed and asked forgiveness, and he did it again after a car accident, but it didn’t change him for good. I don’t see myself ever having a fully normal life. I’d love a righteous wife and kids, but I know my past will leave me with trust issues, anxiety, panic attacks, unpredictable depression and moments of breaking down in front of my future children. I just don’t understand why so many people - family and community - tolerate husbands abusing their wives and let it continue. May Allah give my family guidance, sabr, and protect everyone from harm. If anyone has advice or has gone through similar things, I’d appreciate hearing your thoughts.