disppointment again

haix i tot no one in my family will find out i smoke.. in the end my 4th sis did.. its like kinda unexpected for me.. its like after 4 hours and i've eaten a lot of things she still can smell it.. i hate it.. nobody in my family knew for 2 yrs and suddenly *poof* one of them knew bout it.. i dunno why i juz dun like this feeling.. its like i have been disappointing a lot of ppl these few weeks.. like mr anba.. my 4th sis.. and my friends.. wit everything i've done.. i just feel so wrong.. everything i did its like WRONG.... why why why.. i wanna leave this world.. can i? but i also wanna do something great for my life.. just what is wrong wit me??!! sometimes i'll wonder why am i here? my mom has 6 chilren and after 12 yrs they still wanna have me but don't have anything to raise me up.. all they do is to kick me around to my sister if they can find a place.. they said i'm troublesome.. i feel tat i'm just a burden for them...