Well first of all mrlonely, I just wanna point out that your parents are being ignorant asses. My mom's mother always had her infamous saying "oh, don't be silly" at everything that was bothering her. Somehow some parents are stupid enough to believe that if they tell you you're feelings aren't valid, you'll suddenly believe it's true and everything is fine.
I obviously can't say if you are actually ugly, seeing as I've never seen you, but I'm pretty sure that you have an exagerated view of how bad it actually is. Lets face it, almost all of us (Myself especially included) pick apart the smallest flaws on ourselves and blow them out of proportion.
Something you'll learn when you get out of highschool is that teenagers can be the biggest A-holes. I don't know what's wrong with them, I don't know why their pathetic underdeveloped brains can only derive self-esteem by being pricks, but people like you and I are a cut above the rest in this respect; having a faster-developing brain that can distinguish logical course of actions from instinctive mechanisms of security by demeaning others for no reason.
It guess it doesn't help that we're not allowed to punish kids in school now either.
Anyway, I've prattled on long enough. I just wanna say that, as I learned at the age of 19, when you get to college everybody's mindstate totally changes. Actually it changes a lot for the better at grade 11, but by college it's really great; people don't act like ignorant jerks toward each other just for the kicks, and they're usually really understanding. I was bullied horribly throughout my highschool years and through many schools, but I never had a single person act like that to me in college.
btw, I think you should talk to school counselor, seeing as you're parents seem to be a little impaired in the empathy department.