It's sort of like that... Ish.
An existential crisis isn't exactly morbid in itself. It's just psychologically jarring and crippling.
It's a point where one starts to realize that they might be alone and insignificant. They're just dust in the wind of the grander scheme of things, small and pointless. Without a belief in some sort of deity or having some reason to exist, things start to take an ugly turn towards looking at things in a negative light. Thoughts become darker, there are more "What ifs", you feel worthless, you feel like nothing you could ever do would actually matter. Eventually, complete and utter self-awareness sets in and you start to think you're halfway going crazy. Your thoughts are scattered, you're depressed and nothing brings joy. Existentialism is a very lonely philosophy.
It pretty much blows. I assume it would blow more for those of the feeling types though. There's a reason they call it a "Crisis" instead of a "Realization".