GIRLS how come she did this.?

My ex left me in october and humilated me now she parties and hooks up but I stay home and write songs and play guitar. Last week someone wrote something in her,locker and blamed it on me. And over the weekend I heard she blew one of my gradeschool bullies who made fun of me for dating her. Im fifteen btw but shy and dobt drink party smoke or hook up. I try to stay true to myself. We went out for two,yrs. I always treated her nice :( email me at cgrant_95@yahoo if u want more details. and no it wasnt a little kiddie romance we did a lot but i dnt like "bragging" bout tht