Family issues I NEED HELP!!! PLEASE?

it feels like my parents dont care about me (live with grandma and grandpa) i have no 1 2 go 2 no counceller no dad (2 busy with my step mom and her kids) and no mom (she died about 7 yrs ago) my grandparents act like they care more bout my sister then me i am older but she is a lier a brat and really bossy!!! now i dont wanna tell them that sometimes i feel like commiting suicide!!!!! i have tried to tell them this "YEAH RIGHT" is there response i am a straight A-B student u would think they r proud prob not... i dont know wat 2 do HELP ME PLEASE how do i show them i have had enough without telling them and btw they nvr let me leave the house WITHOUT them im 13 not 5!!!