How to tell my parents i cut myself?

Call your doctor now: I'm not a pyschiatrist but I do know some stuff. Young people tend to self-mutilate when they are trapped in impossible situations, just like animals in the zoo may do. If your physician or parents discover this behavior, they may simply say you are mentally ill. If instead you talk with your physician about your home situation, he/she may be able to intervene or otherwise get things fixed.