Oh Mrs. Columbo... I'm so sorry for your loss.
There is alot to be said about dogs not recovering from loss, When my ex lost our chocolate lab (4) he was out with our mutt Sadie. She was 15+, blind, almost deaf and she got hit by a car. My ex found them both and when they did a necropsy on the lab they found no signs of trama so my vet guessed that he witnessed the accident and it tramatized him so much his little heart just gave out.
This was only weeks after our divorce was final and we sat and cried for hours together.