I've been studying for 4 years and still feel like I don't really know anything about what I want to do for my career.
how do you deal with that feeling?
I always drink in order to dampen my misery.
Drinking is not a way to cope with that problem. Spend some time talking to others and doing research online instead.
Fuck, I'm scared. I won't know what to do since this illusion of my greatness is coming to an end. I need more booze.
You need to stop drinking so much in these situations. That will not help you make decisions about your future.