How can I get my life back to normal?

I see no reason to make things right but my previous questions.. well everyone keeps lecturing me so yeah I don't really care what I do anymore... My parents divorced, my dad moved out. My mom calls me a waste of space because I get like one or two B's on my report card. I'm a perfectionist, I want to cut myself, I want to die. My only motivation is knowing I have to help others. I want to become a humanitarian and I've always wanted to dedicated my life towards others and now it's making me forget mine. I cry all the time because I feel like no one cares. My best friend ditched me for some rebels who were "cool" and I'm such a klutz and stuff. I always embarass myself. I'm only happy with my friend Jack and my friend Katherine. We've become close friends and they're great, but I know they won't understand. My idea is to just try and give myself a new identity. I want to 4get this old life, hide my emotions even in front of myself (I only cry when I'm alone) and become the beautiful, flawless helpful person I've always wanted to be. I mean at school apparently I am her cuz everyone compliments me and stuff but it's all fake. I'm not that person. How can I really be that person I make myself out to be? Does my plain work or do u have other ideas? I just don't want things to get out of hand before I've actually stopped being selfish and helped the world.