I would always recommend bleaching before a cosmetic dental procedure. It is easier and more practical to whiten the teeth as much as you are able and then match the restorative treatment to the new lighter shade.
This can happen if the peroxide that is in the whitening product comes into contact with the gum tissue. It should return to normal soon. If this happens more than once, you should consider having custom bleaching trays made to the precise shape of your teeth. The type my office makes is shaped to stay off the gumline. Your dentist can give you some more advice on different types of products that will probably work more thoroughly and are less likely to contact your gum tissue.
I suggest that you try not to worry about his opinion any longer. You got your refund and now can feel free to go to another dentist (who hopefully will treat you with more respect) Good luck to you, I hope you can find someone with better manners.
