If you were to kill yourself, people would be sad. People would probably cry, and remember you, and talk about you, and make jpegs and post memoriums for you on Myspace. But that would last for...maybe a month. And then
people will start talking about you less and less. At 6 months, the only people who would even remember what you looked like are your family and close friends. People in school would move on. Forget you. Throw parties, get drunk, have irresponsible sex, sleep, eat, laugh, cry (about shit besides you) graduate, and move on to adult-hood, maybe thinking about you...twice through the whole thing. By the time a year has passed since you died, days, maybe even weeks would go by without your name being brought up by ANYONE. Your parents might even have more kids. To fill the gap you left.
Regardless of whatever anyone ever tells you, human life is completely expendable. You don't matter, I don't matter, the world will move on with or without you. Just some shit to marinate on