My parents only protect my older brother

My brother has treated me and my twin sister terribly ever since we were little. If it was locking us in a room or throwing things at us even ripping up drawing and cards we made him because he was mad at us. I have an issue with anxiety and one day he got so mad that he yelled in my face
Calling me mentally ill and saying that it makes sense I’m on medication. I’ve learned to forgive him but he keeps having these outbursts. I tried to confront him but again my parents keep saying he is sensitive and we need to walk on thin ice around him. I don’t think this is far and on top of that I’m 16 and he is 20. Now I’m supposed to treat him like a baby? I’m really tired and so is my twin he has hit her before and that still isn’t enough for my parents to discipline him