Advice on how to move on and be happy please : ( i cant do it alone?

im 17 turning 18 in ...8 days. i dont have any friends, my sister isnt in my life, shes a year older and my brothers arent in my life .. they are in their 30s. i dont talk to my parents about anything either, were distant. everytime i talk to my sister she makes me want to cry. everything she says, she says it hurtfully. she is suffocating me. she has to no everything about me and it drives me crazy. everyday i think ... what if i werent here, then i wouldnt have to go through this ****. im crying right now. i dont have anyone i can talk to.about anything. i am nice to everyone but everything i do ... doesnt even matter. i dont fel important i feel like im useless. i act like im ok and everything good but when i go home i cry my eyes out and noone knows. i dont have a social life. i try to have one but everything fails.i dont know what is wrong with me. i hate my life and wish i were never born because noone likes me or ignoliges me. everyone notices my sister over me. i wish i didnt exist. i hate myself : ( . the only thing that will make me happy is when i move away for school. i am spending an extra year of highschool to apply to prestigeous universities and im prove my grades, to get a 90 average. when i move out i will be happy. but thats in a year, life is miserable now. i have a year of helll coming and dont know how to handle it : (