I too was afriad of talking to my parents, and rarely do. But telling them once was enough to get help. If they are supportive then all they need to do is help you get the professional help, you don't need to tell them everything, just say I want to talk to a counselor... or try your school, and see if the counseling center may be able to help, even without telling them.

Then the only thing you have to answer is what Sannah posted.