This subject, is quite...difficult. Whilst telling an Adult or Authority figure is a good thing to do - ultimately it can be detrimental in a way that the Adult or Authority will not help you. Not saying this happens often, but in some areas the Teachers, Adults, Authority are in on the bullying and find the Victim to be the catalyst or antagonist of the problem - not the abusers.
Notify your parents, and if they are literally beating you physically, go to the police with your parents - that is Assualt.
Tell someone, just becareful with who you are telling - from personal experience I went to the Head of Discipline at my School many years ago to get the bullying to stop, he did nothing - except for encouraging the bullies to keep going or just waving it off as 'Kids will be Kids'.
This happened at the other school I went to as well, I am going to be honest here - the system doesn't work in a way to benefit the victims - its just about silencing both sides of the story to make it look like it never happened or was a misunderstanding.
The best things you can do for yourself is to notify people near you, Family, Friends and any Authority figure you can trust, if they are cornering you and punching/kicking and whatever - GO TO THE POLICE - and if you can, record the incident via an audio recorder, have some evidence.
Go to a Counsellor and speak to them about this, let there be a record that can be used if you are called into question.
Magic wise, there is a lot you can do, the amount of Curses out there to stop/harm abusers is a long list - personally I would go with more Safety/Self-Protection Spells, spells to Bind or to help you get through this or make people favour your side more.
A harming spell is a 'quick fix' in a sense, you just want out, that is understandable. But something I've been taught aout Bullies is to think, think before you speak, think of what you can do to get out of the situation, think of another course of action to take besides harming another - for in some instances if you do punch your bully and there is no record of the fight, you can be done for assualt as well. That is why the System doesn't work for anyone.
Try and avoid them, walk away from them, don't react to their nasty calls, but record them, write them down, audio record for evidence to show that this is more than just 'kids being kids'.
Stay strong, stick to what you know and find allies in those you care about, you're never alone.