Firstly, I’m so sorry you have to deal with an abusive sibling. Honestly, that must feel pretty betraying to have someone in your own home hurting you either mentally or physically. It’s not right, but I know talking to a parent about it doesn’t always do anything.
It really hurts when you try to make yourself better and all you hear is “But you used to, so you still are”.
I am so sorry you go through that kind of thing. I know you’re different, and Im pretty glad you are. Im sorry other people just can’t forget what your past was like. Goodluck with your new school,