How do i stop being so sad?

im 13 so far my life has been full of death and hate my dad left my mom after she got pregnate my mom lived with me and my great grandparents for years then my great gma died of cancer and my dad killed his self my great gpa kiked my mom out of his house my mom got back on drugs i am currentlt living with my grandparents and they tell me all the time how much they hate me they hit me with belts for no reason and ive become so depressed i staarted cutting myself the only people who like me are my techers all the kids at my school think im weird someone please please help me