I have a friend who is very suicidal and the school knows and he's still around. Allthough he has help for it.
But check out this awesome workbook it may be of some help to you. I found it to be very helpfull.
http://www.katimorton.com/sh-workbook-vol-1-sign-up/
t's totally free So I'd try it if I were you.
Also try to keep it from becoming an addiction. I know like you feel like you crave it now. But really the earlier you stop the better.
Also your grandma might just not know how to coop with it.