Literally just had a similar thing happen to me. Cure that one-itis (like Ice says, new girls are the best remedy) and and move on my friend, those girls that are still hung up on their ex's aren't worth the torment.

Also, it can come off a little childish deleting contact numbers etc. but I find it works for me. Just make sure you stick to your guns, you're gonna look foolish trying to get her number again.