I had the experience of taking a diabetic cat to the vet today, because he was having seizures.
It was very traumatizing for myself and my wife. Its one of those things, where you don't really know how much you enjoy having a cat around, until he is not around. We went back to the house briefly after word to calm down, and it was weird having the two cats there without him.
He is going to be OK and he is coming home tonight.