My brother abused the girl I’ve always loved and now she’s asking me to choose

I'm stuck between my family and the only woman I've ever really wanted.

We dated briefly years ago. It was short but it meant everything to me. We broke up over something dumb and she needed to focus on college. No hard feelings.

Then I left the country for work. My brother moved in on her while I was gone. Everyone told me to let it go. So I did. They stayed together for years.

Now they're broken up and she finally told me the truth. He was abusive. Physically, mentally, the whole nightmare. She was too scared to ever report it. I believe her completely. She wants me to help her put him away. And she wants us to finally be together. Says she's always wondered about the "what if" with me. We've even talked about marriage.

I've never stopped loving her. Not once. I stayed quiet all those years because I thought I had to.

But now I'm trapped. I don’t like my brother but if I help her, I lose my family. They've always had his back. I'll be the traitor.

I just need someone to tell me what to do.