Why does my math techer hate me ?

Yes! Ugh I had this one teacher in the 7th grade who hated me sooo much. She hated my two best friends to, but she was mainly after me. LIke everytime I would turn in an assigmnment, shed claim that it would go missing and give me a zero! Then when she would give out papers, shed throw mine and my friends papers on the floor! One day I was really really sick and I had to vomit and she wouldnt let me go to the restroom. So after like ten minutes I felt horrid and weak, my friend helped me walk to the bathroom. She got sooo pissed off and started the entire school searching for me! She told all the teachers I was trying to run off campus and that I needed help! So all the teachers were looking for me! Then my friend and I came outta the bathroom and she was like waiting right there! She ordered my friend to go back to class and when the hall was cleared, she started yelling at me and even grabbed my wrists and started shaking me!! The bell rang and the entire class saw but when the principle asked for witnesses no one stood up for me except my friends and they didnt believe them