HELP HELP HELP

i’m 17, in high school. The doctors told me i have depression but i still don’t believe its real. It’s unbearable sometimes. Humans have glass hearts meaning we are so easily emotionally crippled. I just ripped two of my stitches out ( I DONT CUT I Tripped on stairs and the rail edge thingy cut my arm ) because there’s only so much pain you can take, you know?  My father lost his mother, thus leading to him to scream at my mother, thus leading to her yelling at me. She tells me I’m worthless, a failure, that its my fault she’s going insane and that I a going to kill my father because he can’t sleep at night and I can’t stop crying after one of her blaming/yelling fits. I forgive and love them both, its just, when she has told me that multiple times it hurts. My father does nothing, just pretends he doesn’t hear. Sometimes when she yells at me and I lose my control, I yell hurtful words back at my parents, thus hurting them.  I try not to believe her, but I admit she’s convincing. Am I destroying the family? Am I selfish, immature, and worthless? Am I accountable for the emotional pain my mother blames me for? Am I a selfish person who needs to grow up? Am I killing my father? I find that my refuge is to go to my friends houses and crash for  a couple days. The answer is to help my parents through the pain they are facing, and to properly communicate. Communication is key. However, if you believe I’m doing something wrong, please tell me. It would help so I can fix this family crisis.