I'm so sorry!
It sounds like he waited all day for you to come home.
From that photo, here was absolutely nothing that you could have done to save him. The colour of his comb is quite shocking and he was clearly incredibly weak and at death's door.
I hope it is some comfort that he had a good life with someone who truly loved and cared for him and that his memory will be cherished. Maybe if you are artistic you could do one of those plaster of paris foot imprints and decorate it with a few of his feathers and make a memorial plaque from it to hang on your wall.

From that photo, here was absolutely nothing that you could have done to save him. The colour of his comb is quite shocking and he was clearly incredibly weak and at death's door.
I hope it is some comfort that he had a good life with someone who truly loved and cared for him and that his memory will be cherished. Maybe if you are artistic you could do one of those plaster of paris foot imprints and decorate it with a few of his feathers and make a memorial plaque from it to hang on your wall.