omg, trust me I know how you feel!
I don't know how many times I've been called ugly or fat by people I hardly even know! and people that I liked! I was mortified for so long and I just started thinkin to myself...you know what, if that person is so shallow that they have to put me down to feel superior then I am SO above them. If she can't even be considerate enough to keep her big mouth shut, ESPECIALLY, when she knows that you're there, then she doesn't deserve you.
You don't want her! You'd have to sink to her level and then you'd just be short (tehe, I kid) but seriously, you're so much better than that, and you're such a cutie! Don't let her get you down. You're great! love ya zach!