What should i do?

my mom n dad dont treat me bad all the time somtimes there gd parents i guess but they are very moody n i dont kno when its safe to tlk to them cuz im extremely scared of bein yelled at cuz thats all they did when i was a child i mean for a whole year if my dad wasnt yelled at me he was callin me fat n stuff (how i stopped eatin for a whiel n excercisin extremely) my mom seems to just be hatin me more every year tht i get older my parents made me get homeschooled pretty much to cutt me off frm ppl im only allowed to see my friends less everyother day 1 or 2 of them and i have 2 mentally retarded brothers who have angery problems n hurt me when ever there angry pretty much n they see me n im there number oen target and when there hurtin me i try to defend myself the best i can while my mom is yellin at me n then afterwards she yells at me some more she always defends them im startin to feel depressed and worthless in this world i really dont kno wat to do plz help