You asked

"What's the scariest part?"

I answer;
"the scariest part is not the feeling of
loneliness
Or the darkness that fills you
despite the looming pain,
Of emptiness.

Th scariest part
Is the realization
That you have lost yourself
completely
Sinking in as you lay awake
At 2am
because you lost the ability to sleep
and you can't even try
because you don't even care."