Life begins on the other side of despair.
If you've never read Sartre, don't do so unless you're ready for a head trip. The Existentialists aren't an easy read on the best of days, and Sartre was a master of the philosophy, which means you'll walk away feeling as though your brain has been pounded, stretched, stomped on, and pureed by many large men in spiked boots. However, there are many truths in Sartre's existentialist worldview, including the fact that hell is other people - and spending an eternity with them in a room filled with Second Empire furniture.
I highly recommend No Exit. Then, if your brain isn't suitably pummeled, try Herman Hesse's Steppenwolf. Then consider that I read both of these when I was still in high school, by my own choice, and you might begin to understand why I'm a little weird.