How to cope with confidence issues?

People say im pretty but i always feel ugly and gross. I am always the victim of jokes. Here's one time: this one guy was in a fight with some one so he yelled over to me:'zach wants to go out with you!' this zach person said: ew! No! She's gross! I felt like I was shot and I could've killed them both. That has happened to me about 3 more times. So much, I used to like the way I look, but now I find every imperfection I think I have and I find lots of them. I harm myself trying to 'fix' them. I spend up to 3 hours putting on make up so I don't look the same, and I cry 3 times or more a day hating myself. I hate hating myself, how can I feel better about myself again? Anyone want to protest against how I feel ugly? Here's how I look. a href="http://imageshack.us/content_round.php?page=done&l=img21/9016/0606111713c.jpg&via=mupload&newlp=1" rel="nofollow"http://imageshack.us/content_round.php?p…/a