I don’t know your situation, but turning from family will only harden their resolve and make them more defensive. I went through this with my mom. She voted for Trump in 2020, after years of me telling her how bad he was. I was angry and didn’t talk to her for 2 months. During this time I heard a podcast with David McRaney, about how to talk to QAnon people. It helped me to understand how they got there, and how to help them out of it. It is a process. They operate on an emotional level, and you have to relate to them on emotional level. After that, you question how they arrived at their decisions. Like:
If I asked what your favorite movie is, could you explain why it’s your favorite movie?
Emotionally connecting with them and then thoughtfully questioning their beliefs, in a non-condescending way can be beneficial. It may take days or months, but once the seed of doubt is planted, it can start a dialogue. Remember, these are people we love ❤️, we owe it to ourselves to be compassionate in conversations.
It certainly sounds like you made the right choice for you if there is a violent history. Hope for the best for you and your brother.