Is it my fault I'm in this situation?What should I do?

Before I really enjoyed talking to this one guy in my biology cl and I thought of him as a friend more than a clmate. I DON'T have a crush on him. He got a girlfriend and her friends sit next to where I sit in the morning. One day, he comes and asks for help for his homework so I letted him copy my report . Then his girlfriend's friends start to taunt me in front of me and this made me uncomfortable and awkward even though I'm with my friends. Everyday after that they tease me in front of my face everyday at school in the morning and when they do I really want to cry. Is it my fault I'm in this situation? What should I do about this? I really don't want to enrage them .