i have troubles with my ex gf, what should I do?

My ex girlfriend doesn't accept the fact that our relationship is over. I left our relationship because she said she loved me one day and she said she hated me the next! I tried EVERYTHING to understand why she behaves this way: I tried giving her some advice, I tried to notice if she was talking about another person, I tried not to listen to her insults, I even tried to text her but she didn't answer! nothing worked. She thinks she is hopeless with love and relationships so she is quite depressed. I know that what she thinks is quite true, but her behaviour just doesn't make sense! I described the situation to my parents and they said she's an idiot and I should stop caring about her because she's only playing me. The worse thing is that she thinks I am the one who is playing her! I don't know what to do, she argues about everything I say, she doesn't listen to me, she tortures me first and then she wants me back! I'M NOT HER TOY TO PLAY WITH! Now she keeps harassing me and she even made friends with my classmates...T.T I think she's quite psycho. What should I do???