Assalamu alaikum - Need advice: stuck between family, an arranged cousin marriage, and parents' breakdown

Assalamu alaikum. I’m a Muslim man in the UK from a West Asian background and I need some practical advice. A few years ago I found out my mum and her late brother had basically arranged for me to marry my cousin. I had no idea growing up and I was strongly against it. When I said no, my parents used heavy guilt and emotional pressure, saying things like “you won’t honour your late uncle’s wishes?” and “how can you reject your aunt’s daughter?” I eventually agreed just to stop the constant pressure, though my heart wasn’t in it. There were other pressures - my cousin’s parents were worried because she’s older than me and wanted things to move ahead. Around the same time, our family went through a big change: my dad follows the Ahmadiyya sect and a few years ago my mum and siblings also joined. Before that my parents used to fight a lot, even physically. For a while after the conversion they seemed calmer and I felt relieved. I’d planned to go for Umrah with my parents and my cousin travelled there so we could meet, because I couldn’t safely go to her village - some people in our area were hostile after they learned about my dad’s sect. I went along with meeting her mainly to get the marriage arranged because of the pressure. Now things have fallen apart again. My mum has stopped believing in that sect and she wants a divorce. My brother also told me he saw flirtatious messages between my mum and another man; my dad doesn’t know about those messages. Yesterday my dad grabbed my mum during an argument and physically kicked her out of the house before things were calmed down. My mum told me she can’t take it anymore and wants a divorce. I’m in a terrible position: - I don’t want to marry my cousin. I felt forced into saying yes and I still don’t want it. - My mum wants a divorce and is unsafe at home. - My dad doesn’t know about the messages my brother saw. - I have younger siblings who depend on me and I worry for their wellbeing. - My mum’s English is limited; if she’s kicked out I don’t know where she’ll go. - I feel torn between protecting my family and doing what’s right for myself. I’m overwhelmed and scared. I want to handle this in a way that protects my mum and siblings, avoids forcing a marriage I don’t want, and addresses the conflict between my parents without making things worse. Can anyone advise practical, Islamic-minded steps I can take? For example: how to seek immediate safety for my mum if needed, how to involve community support or local services without inflaming the situation, how to address the marriage I don’t want (is it valid if I said yes under pressure?), and how to approach the parents’ conflict in a way that keeps my siblings safe. Any dua suggestions or verses to keep me steady would also help. JazakAllahu khair.