AITA for telling a friend what my brother did

10 years ago I went on a family camping trip with my parents, my brother and his partner and my then partner.

During that trip my brother was repeatedly rude and derogatory towards his partner, snapping at her and putting her down constantly. Towards the end of the trip I called him out saying “hey, I don’t think you should speak to her like that” and he ran over and pushed me out of my camp chair and onto the ground. The next morning he left.

He bullied me a lot when we were children and frequently used his much larger size against me, but we were kids.

About 18 months after that trip on another family holiday when I was heavily pregnant I made a comment to my mum about him being grumpy and again he ran at me and screamed “why do you always have to be such a little c@&#” in my face. I then went into premature labor the next day.

Some time after this I was talking to a friend who happens to be friends with my brother’s partners sister about my relationship with my brother. She asked me about if he had ever treated his partner how he treated me and I told her about that camping trip and what had happened.

Things have otherwise been fine over the last ~10 years. We both have kids now, he married that partner and we do normal family stuff together. I talk a bit with his wife but he and I aren’t exactly close, but civil.

I have recently found out that he apparently doesn’t want anything to do with me and is only being civil for the sake of our mum. Apparently he is furious that I made “allegations of domestic violence” to someone outside the family, and that he will never forgive me.

Am I the A in this? And what do I do about it now?

TLDR: 10 years ago I told a friend about witnessing my brother being mean to his partner. My brother is still angry at me for making “accusations of domestic violence”. I don’t know what to do