I'm sorry about your situation I dont know why there doing it. But if I can suggest maybe switching universities, you may find a better one where it maybe a bit easier for you to cope.
Bullied and harassed are vague statements. Can you say what it is they are doing? There are legal and political mechanisms to fight back with, but without knowing more about your situation we can’t really guide you the right direction. Since you are posting in the mental health form I am assuming that you situation revolves around a mental health issue. There are lots of groups that offer advocacy to people with psychiatric diagnosis (some groups are better than others). Check to see if there are any such groups in your area. They might be able to help.