Hi, Laslo, and welcome.
You've got a lot you're dealing with, there. I'd suggest as a first step, getting yourself (and your grandma, if she will go) to Al-Anon. Not only will you find a lot of support there, you can learn ways to deal with the effects of your grandfather's drinking. Has he been a hard drinker/alcoholic all your life, or is this something recent? Does he go to the doctor? You might also find some help from your local agency that provides services for the elderly.
How does grandma cope with all of this?