What should i do........?

Wellll im 17 and yea my life kind of sucks for like the past two years, things are so complicated, i have no friends, my brothers has gone to prison and well i looked up to him and now he's gone im here the oldest feel like i gotta make sure everyone is fine but they're not they're falling apart right infront of me, his baby born 2 months ago was going to go into care and our mum(babys grandma) has fosterd and will be adopting but i mean age 47 with a new baby is put my mum on anti depressants and shes all crazy and stuffff :S so coz of that i dont have a room at my mums any more and i have to live with my dad which i HATEEE. i failed my a levels, so im starting fresh to do a diploma and hopefully become a paramedic...but well uhm me and drugs have a history, and right now i have the cash and people have been offering my 'coke' im trying but i dont think i can resist any longer, i dont want to damage my brains but ergh i need to feel good for once!! dayumm i have no one to talk to i have no mates no one bothers with me, well i did withdraw myself but didnt realise if you get that, so yea no one knows what to really think of me.. :/