> When I needed medical attention, I was helpless to help myself survive.

This is really poignant considering that he tried to handle this himself and refused conventional treatment for months - likely causing his death. It's interesting that he doesn't seem aware of this even afterwards, but it's probably for the best.

I guess the whole letter explains a personal crisis and probably explains why he did what he did. Is there any more writing from him on the subject?

He said something similar when he was 28 at a design conference: https://youtu.be/t9HmOz8H0qI?t=2827 at 47:08