Don't care about anyone
Do it by urself

Bc my bsf and ma principle will kill me

I cant

Then the principle will beat my ass if I do 🤒

Go to that kid ask them to apologise politely
Ik they will say no.
But if they bully you again then js punch with your 70% of power straight on her nose
Then kick their leg from back so she will fall on ground.
(Don't hit them first, do something so they will hit you first) or ur dad will beat you