How do the philosophers/you guys deal with an existential crisis?

the title is what it says, I'm having an existential crisis and I'm 18 years old. I just got off having taken aripripazole for a couple of weeks and I don't know what to feel recently, i just graduated High school and I feel like life is inherently useless, everything is temporary and there's no use for anything in life. It's such a useless thought but I've been feeling so depressed over it. I sense time in the way it passes, and it makes me feel weak, I don't know what to feel and I'm hoping you guys can give me books that explain this feeling and if there are philosophers that have tackled this?