The only thing that truly terrifies me about dying is the thought of being conscious, or somehow remaining aware of myself throughout eternity. Stephen King's "Jaunt", Junji Ito's "The Long Dream", Black Mirror's "White Christmas", SCP 2718, or, the granddaddy of this sort of thing, Harlan Ellison's "I Have No Mouth And I Must Scream", all, to some degree or another, illustrate what I'm talking about here. The idea of time dilation taking place during the very moment of one's death is something that disturbs me greatly, although I'm not sure how it'd happen if somebody just blew their head off with a shotgun. Another thing that deeply disturbs me is the spurious notion that wherever you "think" or "believe" you're going to go, is exactly where you go. What if you're an obsessive basket case like me though, who can only fear & hyper focus on the worst possible scenario? What then? Am I just completely fucked? Literally condemned to hell because of OCD I was cursed with and that I can't control? Honestly that whole thing, along with "The Secret" & authoritarian mindfulness garbage in general, is some serious "It's A Good Life" Twilight Zone bullshit. "Only think good thoughts & beliefs now, or be condemned to eternity in your own personal hell!" I remember first hearing about this kind of thing from George Carlin on one his comedy albums (Brain Droppings, I believe it was) and, ever since, it's been something that's both enraged me & made me shit my pants, in equal measure. Even pessimistic, cynical me, honestly can't admit to the universe being that badly/maliciously designed, although, in some sense, it'd be very fitting if it were.
It's also frightening to think how someone who's paralyzed and has no use of their senses is pretty much trapped inside their body, akin to being trapped in a black, endless void. Just think of that guy who failed at shooting himself, becoming practically a vegetable in the process, and kept blinking how he still wanted to die. Dude must've been howling, blood curdling screams on the inside 24/7. "Johnny Got His Gun" is another unsettling story that detailed this sort of thing.
My reassurance against all this awfulness? Well, mostly the obvious. The mind sits at the center of everything. Once it goes, that's that. Like switching off a computer, or flicking the off switch on a light. It'll simply be nothing. Like a deep, dreamless sleep. If I knew that were the case with absolute certainty and that every part of me would be completely annihilated in the process, then I wouldn't have the slightest but of concern about death. Dying certainly, but not death. Funny how something like Hamlet's famous soliloquy on death & dying, written hundreds of years ago now, strikes right to the very heart of this sort of thing.
The fact that one would potentially still have to be alive to experience that sense of eternity isn't a exactly a great comfort, though. Quite frightening itself in fact, given the dystopian hellscape of this planet. Perhaps there will be drugs that can simulate what I've described above in the future as a form of capital punishment. You'd also sure as shit never catch me uploading my consciousness to a computer (assuming we're not in one already), since death, in the sense of it being a dreamless sleep, would be impossible, whereas any sort of hell you could imagine, would suddenly be a reality, whether due to a bored hacker, or a nightmarish cyber government. Even if that weren't the case, just imagine if the program ever got corrupted somehow, leaving one in a potentially literal version of SCP 2718 due to that corruption.