You most definitely did the correct thing in neutering!!!!!!!!!!!!
The vets here would have kept the animal until it was fully awake so you would not have had to see them in this groggy state. The most likely reason is exactly what happened to you, you pannicked, thinking it was a bad thing. Just remember that if he had any other operation, one to save his life pehaps, he'd have that groggy feeling and you would not feel guilty, would you???
All pets should be neutered if for no other reason than stop accidental litters, but there are SOOOOOOOOO many other benefits from it.
You can still get him that "wife" I am sure he'd love a companion, just make sure to spay her as well, because not everyone will and dogs may roam into your area and make her pregnant.
The myth that animals get fat if they are neutered will only become true if they are fed more food than they can burn off with their level of exercise. (but then this is true of un-neutered as well). In other words it is NOT the neutering, it is the amount of food.