Wow

I opened my mail today to find a handwritten, incredibly sad, and absolutely unexpected letter, one that the writer felt was long overdue.

I'm simultaneously filled with joy, sorrow, and excitement. I'm also

gobsmacked
adjective, slang
Flabbergasted, astounded; speechless or incoherent with amazement.
(prob. from Irish/Gaelic gob, mouth + smack; literally, smacked in the mouth)
"gobsmacked." Worthless Words for the Day. Michael F. Fischer, 2005. Answers.com 19 Jun. 2006. http://www.answers.com/topic/gobsmacked