As a hijabi, I had my fair share of hijab pulled...Consider it an initiation process...But it stops around ninth grade. People suddenly grow up...Although you may still get some deriding comments about it occasionally. But generally you'll get nice comments, and curious questions, and lots of support.
Anyways, I remember you said you have brothers. I think one of your brothers should go to talk to him...my bro always took care of things like that for me in a very nice manner really. He would just talk to him privatly, and say "hey, i know you pulled my sister's hijab the other day, waht made you do that? what if this was you sister? " It would never happen again after that. No yelling, screaming, or cursing; just calm and cool.
Or sometimes I talked to them directly too. Privatly of course, so as not to embarrass them. THey usually said sorry and never did it again. I remember when we wre in the older end of high school a lot of those same people that pulled my hijab ate lunch with me. Some people just don't think when they're doing stuff especially at your age.
As for your friend...her behavior was out of peer pressure, and she's probably gonna regret it later on in her life. Drop her for now, but she'll probably change when she's older, so extend the olive branch when she's ready too.
In other contexts, I've been in her position at about her age. I wasn't the nicest person in middle/high school...everything was all about me then, until I realized other people were not my servants. It's just the way you're raised. I was raised like a princess among brothers, and got everything on my first demand. Not that that justifies anything but I learned a lot from those that were ready to forgot petty details of our childhood past. It looks really stupid when your 20+ holding grudges of things that happened when you were teenagers.