I need some advise to quit cutting myself.?

I have been cutting myself for 4 years and I have tried to quit countless times. Every time I feel sad I turn to cutting. I want to quit badly. I have almost died once by cutting on a vein that if cut can kill you. My grandma saw and started crying and worrying. My teacher saw and made fun of me which made me cut more. I need another way to handle my problems. Any suggestions?