From Ironic:
An old man turned ninety-eight. He won the lottery and died the next day.
Well, close. The guy, Donald Peters of Connecticut, was 79, and died the day he bought the tickets:
Peters bought two Connecticut Lottery tickets at a local 7-Eleven store on Nov. 1 as part of a 20-year tradition he shared with his wife Charlotte. Later that day, the 79-year-old retired hat factory worker suffered a fatal heart attack while working in his yard in Danbury.
On Friday, his widow cashed in one of the tickets: a $10 million winner which, in her grief over her husband's death, she had put aside and almost discarded before recently checking the numbers.
I think that falls under the dictionary definition of "bittersweet".