Salaam - Need Advice on Parents' Marriage Struggles

Salaam. I hope you are all well. I need some advice about a difficult family situation. My parents married in 1996. Before I was born they lost two babies in infancy. I was born in 2000, and after me my mother had ten more children - eleven of us in total, alhamdulillah. From 2001 my father started marrying other women. Many of those marriages ended for different reasons - some for incompatibility, and others because those women were disrespectful toward my mother, which he would not accept. Those events hurt my mother deeply; over time she became numb and stopped showing much emotion. My father has always provided for us: good schools, food, and a lot of sacrifice. My mother has been an amazing, caring mom. But there is a major issue that changed everything. When we were young, my father was physically abusive toward my mother. He beat her badly at times, leaving bruises. This went on until 2009. I remember one night in 2009 very clearly - my mother was nursing a baby and my father attacked her. He tripped her and stomped on her back while she couldn’t defend herself. We tried to step in, but we were kids and couldn’t stop him. After that he apologized, bought her gold, and promised never to hit her again. He kept that promise and stopped the physical abuse. By the early 2010s my father had built considerable wealth, roughly a few million dollars. In 2017 he invested almost everything into properties back home in Somalia. By 2018 his businesses started failing and he couldn’t sell the properties. He took loans hoping to recover later, but things didn’t work out and now he is in heavy debt - around $350,000. Now he is struggling financially and can’t provide like before. My mother refuses to tolerate the situation. She blames him for his choices, especially marrying multiple women, and says she won’t be lenient now since he was never lenient with her before. When we tell him this, he asks for patience and promises he will provide again eventually. A few days ago my mother called him and he hung up on her. He says she often yells on the phone and sometimes he is around people, so he tells her he’ll call back to avoid exposing their issues; that makes her angrier and sometimes he hangs up. My mother sees that as disrespect. She asked for a khula/divorce. Last night my father came back from safar and first went to greet my mother. He congratulated her on a new business that’s doing well. Instead of thanks she told him she wanted a divorce. He refused, saying he loved her and didn’t want divorce. Things escalated: my mother started throwing things and physically attacking him. We tried to calm her for hours, from about 10 p.m. to 2 a.m. Over the past two years my mother has gotten more irritable, quick to interrupt, easily angered, and she often criticizes my father even when he suggests reasonable things. I worry this might be mental health deterioration from years of trauma and emotional neglect. I understand both sides. I see my mother’s pain from past abuse and the way she’s been treated. I also see my father’s remorse and his plea for patience while he tries to recover financially. We, the children, are caught in the middle. Both parents dismiss each other’s suffering, and if we step away things fall apart. We don’t know what to do. Should we try to get them to see a counselor or a trusted imam who understands these issues? Should we involve other family elders to mediate? Any practical advice on keeping the family together while protecting our mother and supporting both parents would be greatly appreciated. Jazāk Allāhu khayran.