Im giving you an honest answer and please dont think im sadistic for doing it.

Get fit, train for weeks, build upper body strenght. Everytime someone insults you use it to fuel your excerise. If those people play by looks then they will crap themselves if you get stronger, try do it over a summer holiday, fresh start.

If they still dont do anything, beat one... I mean beat the living life out of him with that strength. They will fear you and even if your not accepted, thats alot better than them picking on you.

I honestly hope you can overcome this, the power is yours kiddo. If you have the determination, the will and strength you will go back to that school, and rule it but at the same time, not being an ******* to people lower than you like they did to you.

Good luck