Im getting depressed its killing me .. i need advice?

well guys, im the type of girl no one expects to get depressed i stay happy in school and make other ppl happy when i come home, i have lots of responsiblities.. i pay the bills, tutor my 3 other younger siblings, clean the house, balance checks, do laundry, mow the lawn, fix cars and everything im ONLY 16... i dont wanna be selfish .. but i should deserve some respect right? or some appreciation.. my parents.. they dont speak english very well, and u can guess dont know how to use modern things (computer), plus on top of all that im taking the most hardest and demanding courses at my school (international bacchleraute) well to the point.. my sister is driving me to the point where i literally want to shoot her.. . shes making my life a living hell.. she tells my mother that im turning bad.. i curse at her she snitches.. shes always looking out for me to mess up so she can make my life miserable.. and she makes my mom join wid her.. what should i do .. i came to a point where im cryin