Think about the your last line you wrote...you do NOT want to lose your education and everything in life to alcohol.
you know you are capable of putting down the wine glass and concentrating on getting yourself together.
I don't know the circumstances of your relationship with your grandmother, but reactive depression can be discussed with your doctor who can make a recommendation to you. There is a better way to handle it then sliding back down the hill.
I'm truly sorry for your loss, but hope you have some good memories to sustain you too.