Help me please im very scared and i feel lonely?

hi im a 15 year old girl everyday i go to school my math teacher who is a man gets me sent to his cl room everyday lunch time he locks the doors and shuts the blinds he come up to me and pulls down my trousers and knickers then gets his willy out and puts it in my vagina it really hurts i cant tell my mum about it because he said he would kill us both what should I do im scared and in 10 minutes its gonna happen again please be quick and help me !!!