Dear Beautiful People...

I seriously need advice. I was always a curvy girl and as a woman. I'm an acquired taste. I somehow married a man who looked like a movie star before he came to his senses and took off with a model. Our daughter looks like him. I thought that was great! She'll never get made fun of the way I did. 
What she's going through is much worse and Idk how to help her because I never had to deal with stuff like this. Fully grown men pretend to mistake her stepdad for her boyfriend and say he's lucky to have a "woman" like her (she's 13). Other girls are really mean to her and she finds it hard to make friends. In gym class she gets made fun of for being so skinny and girls have pulled her arms and hurt her joking about how they can probably pick her up. She's an avid martial artist but has gotten in trouble for fighting back before.
Teachers buzz her on every wardrobe violation they can dream up. She got sent home for wearing a t-shirt When all the other girls were wearing butt-cheek booty shorts because she put her arms up and her midriff showed. She wears boys clothes all the time because apparently the way her body is shaped is a crime.
Boys her age are scared to talk to her and older men make constant comments so she thinks she's ugly because "How ugly do you have to be if only creepy gross guys your grandpas age notice you?" 
I'm worried this will affect her in future. What do you say/do to make people understand you're a person? For me it was easy. Nobody looked at my face or body so my personality was first. But for her people live or hate her on sight, and most of the people who love her on sight are terrible humans. 
I know this post seems superficial and mean to people who look like...well, me....but it isn't meant that way. It's just that most girls who look like her have moms to match, who can give them advice. All I can do is apologize when, for example, she comes home from school upset that her peers made fun of her for having a fat mom. "I thought your mom would be thin and beautiful...are you adopted?" 
Im ob pretty high emotion right now because I just had to pull her from a school where the principal tried to corner her in his office and everyone was against us, éven the school board. I've always been jealous of girls like her but protecting the poor little thing has become a full time job. I really hope it doesn't get worse!!!