How do Ты forget someone?

i keep thinking about my ex... and its driving me crazy!! i just want to forget about him! like once when i tried to get him out of my head.. i started banging my head against a таблица at school(during lunch) and my Друзья of coarse tried to stop me but yea i banged my head so i could possibly lose my memory of him!! cause its just painful to think about him and its hard!! i just dont want to remember anything about him!! how do i do that!! like get a serious head injury... so i can not remember anything!! cause i realy just dont want to tihnk abou him!! but i see him all the time at school! and its hard not to remembr the good times we had!! i really need help!! :(