My brother is abusive, and it's spreading to others

Trigger warning for violence and misogynistic speech.

For my entire life, my brother has been violent. I spent my childhood being told to 'stop reacting, that's what he wants'. I had things thrown at me, got the most disgusting of insults thrown at me, belittled for being a woman, ect.

Two years ago I willingly made myself homeless (recently got a flat!!) and moved countries to get away from him. He had gotten violent and literally picked me up and threw me into a wall (while I was recovering from a back surgery). The police ordered him to stay away for 30 days but my mother let him back after that time period with the whole "he's my son, he can't be on the streets".

He has a new girlfriend, and for months he's been telling us she's crazy, would hit herself, and start arguments, and unfortunately i believed him. He's an alcoholic and tonight he drunkenly snapped at her. It was something along the lines of "I am a man, I am stronger, you listen to me".

She left the room silently, and went to bed, I heard this happen over a call as I'm still not in the country. I offered my old bed in the house for her to use tonight.

I don't know what to do. He wishes to travel up soon with her to see me. I said no, because I'm not as lenient as my mother and I will just kick him out in the middle of the night if it starts and I can no longer even smell alcohol without my nervous system freaking out.

I suppose my question is, do i cut contact? I know it may seem obvious to an outsider, but I am truly struggling with the choice and I worry about how my other family members will react.

I'm sorry if any of this is triggering for people to read, i now realise it's a bit of a rant, and I apologise for that. I don't know how to support this girl, and I feel guilty for believing what he said about her.