I need help with my emotions (please help me)?

Erm im 15 this year and my emotions(love) is always getting in the way.The story started when i was 15 and i fell in love with a girl,it seems that after i told her how much i love her,she has been avoiding me much more.During the farewell dinner after the last day of school,she then purposely hugged and kissed a guy inorder to get rid of me.Right now,it still hurts when i see her and everytime when i think about it, i feel a sharp pain in my chest and i dont know why.Please may someone tell me how to lose my emotions?I really cant take it anymore.