I dont know what i am doing wrong..

School has started for a month now and obviously i like a boy… he was in my class for the first few days and i could always see him staring at me. I thought that he might like me and slowly i started developing more feelings for him. I have a friend that is friends with him and i told her to tell him that a girl in our school like him but to not say who… he seemed kind of interested but I thought it was too early for him to learn that i liked him. I used to look at him and smile and he still stared at me. Until today. That friend of mine that is friends with him asked me if i am ready to tell him that i liked him. I told her to go ahead and tell him since i started thinking that he liked me too. But when she told him, he just said “who is that?”. He likes my best friend. Im sick and tired and sad. Why does no one like me? Why does this always happen. Why am I so.. unloveable. Im not mad at him or my best friend im just mad at myself. For not giving myself time to love me before loving someone else… What do I do?