How can I get over my ex?

Shes super annoying (that's why I broke up with her), everyone in school just hates her and her best friend told her to leave her alone. She loves Miley Cyrus and Justin Bieber (she 13 and so am I). Theres something annoying and she dresses like a complete train wreck she once wore a pink jacket sandals and cheetah pajama pants. She keeps talking bad about me behind my back (I don't really care about that though.) Shes in my first and last cl (were in 7th grade). She dropped out of a program we were in just because she was to lazy to go through it. I really wish I could bust her over the head with a brick. How can I get over this annoying failure?