You asked
What is 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

The scariest part
is the realization  
that you have lost yourself
completely
sinking in as you lay awake
at 2 AM
because you lost the ability to sleep
and you can't even cry
because you don't even care