Disgruntle Ex-employee/Customer Service?

A few months back I had a job that came in that was an emergency. At the time we were working with a new vendor. The vendor and I had numerous conversations so that we understood exactly what the customer wants. However, the customer who is a disgruntle ex-employee feels that he can be very demanding and insulting. (He thinks we’re all idiots.) I kept giving him updates on what was going and any time the vendor would ask a question I would go back to ask him. It continued to get worse with his demanding attitude and one day he sent an email that the font size was 26 (no lie) and some of the words were in CAPTIAL letters and then throughout the email there were red, yellow and green highlights. At this point I decided to contact our sales manager as his email was very rude and insulting where he was calling me incompetent and made me feel like a complete idiot. I told the sales manager that I was done, and I refuse to work with this customer. There is no need for anyone to treat someone like he did. I don’t care if you’re a customer or not! It didn’t stop there. Even though I don’t have to work with this customer any more he continued the pain he had already given me. He filled out a survey in which corporate received and decided to make an example of his survey as a quality issue. I was never so livid when I saw that this survey went out to the whole company! Talk about being embarrassed and angry. Finally, I thought this was it, it’s done with now and we can move on. Nope! Now we’re having an “All Hands” meeting and I was just informed that they are using this example again. So now I must live through another day of embarrassment and anger. What would you do? How would you handle such a nasty customer and how do you get corporate to stop and realize that this is not acceptable?