When my dad died, my brother tried to step in as my "Dad"

3 and a half years ago, my dad died of colon cancer, and I was only 11 years old. Ever since he died, my oldest brother, who is 23 years older than me (I know, big difference. Catholic family...)has tried to step in and try to be my "Dad". I have told my mom about it and she doesn't seem to care. 4 of my other siblings have noticed it too but 3 of them are all grown and out of our house and can't do anything about it. I just don't know what to do anymore. I realize that he is just trying to help out my mom but he has gone too far, by making the decisions on who and when I can hang out with people, where I can go, and stuff like that.

Anyone have any tips on my situation? Avoiding him doesn't work, I've tried it for the past year...

Thanks!
~LP