So sorry to read that Ptolemy is approaching the rainbow bridge. I’ve been through this stage with several cats now, and it’s usually like that — first the shock of diagnosis, then a protracted, almost imperceptible decline. When the end comes, it's a whole new shock.
You and Herself may soon be targeted by the Cat Distribution System. Over the years, I have observed that, when a feline-friendly household loses a moggy, another eventually shows up to take the gig.