I'm curious about how the letter was found after his death. Who decided to make it public? I'm glad I had the opportunity to read it, but I doubt it was ever intended to be released to the world.
I've read that letter at least ten times. The last five or so times, I've patted myself on the back for not crying, until I get to the postscript and then... off I go again.
And the wiki article: https://en.wikipedia.org/wiki/Richard_Feynman
There are lots of videos of his lectures and interviews on youtube. You should check 'em out.