How do I tell my parents that I self harmed?

Hey, I'm a pre teen and I self harmed in the past. I have these cuts on my arm and I hate them. I'm a cheerleader too, so :(. I want to tell my parents, but I am so worried about their reaction. Ironically, right before I started cutting, I read a book called CUT, so they might believe that is the reason I did it. My mom asked me before if I had suicidal thoughts, and I said, no, because I would never kill myself. I just cut because it releases endorphins and makes me feel happy when I am sad. Please help me! Luv you! ~Infinity