I would tell your hubby about pet stores and puppy mills, outside the context of your doggy. I'd say, "Hey did you hear about the puppy mill busts this past week? I'm learning so much about them and apparently, pet stores buy from puppy mills. Let's promise never buy from a pet store ever again, ok?"
You have the doggy. The best thing you can do now, is do what you are doing: give him a happy home with love and care and health.