I dont know what to do my girl friend dumped me and im crushed?

So i thought it was going to be a regular day and when i got to lunch she wouldnt look at me. Hannah told me that i should be worried and she didnt tell her to shut up because she was teasing me. Then she asks to talk to me and im starting to get scared and my heart is pounding really hard. Then she said she would rather be with someone else and then i ran into the bathroom. Then at mathletes i started to ite into my ski as hard as i could and it left bite marks the for a day. The in english i dug my pencil into my skin until it tore skin. im super depressed and i dont know what to do to get over her. HELP!!!!!