Girls driven away

Hello all,
First, let me tell you a little about myself, I'm in 6th form college here in the UK and I'm 16, not bragging or anything but I've been told I am good looking, and I like to keep fit, etc. There's this girl at school who I like very much and we get on well with each other. I've had another girlfriend in the past year or so, who i have since broken up with because she was spreading lies about me. Quite horrible lies, and completely undeserving I was. Nowadays, people seem to believe her, which means that many people get a very wrong idea about me.
I'm scared that this girl has this idea, and I really want to know how to prove to her that I am nothing like what some people are saying, because I've spoken to her and given her reasons, but I don't think she believes me.

Well, has this rotten girl ever lied about other things? I think that if her reputation as a liar outstrips whatever damage she's done to your rep, that might be your only hope.