Along with "there's a first time for everything, consider also the equally old saying, "you can't please everyone".
As I've mentioned on this forum, I have worked for over three decades in high end electronics sales. I am still employed in a service industry job. People can be very rude when you are in a position where you take their money. Even when they come to you, you are seen either as an adversary or as a peon.
Also add to your list of truisms, "Perception is reality". We all see the world from our point of view and no matter who was right or wrong in your perception, it would be an uphill fight to prove to this client what was actually agreed to. Without a signed contract stating a specific time and date, you have nothing really to fall back on.
You might take away from this experience the lesson to always follow up with a client when changes are made to a previous agreement. Email a note to ensure they are on the same page as you feel was agreed upon. Then you have something to go back to when change orders are made. Verbal agreements and handshakes are no longer sufficient.
We now live in a society where there are a few individuals always looking for a reason to be outraged.
Rudeness comes with that perception of you as less than them. Till the day I pass from this Earth, I will never forget the one client who, after I had greeted him warmly, looked at me and said, "I'm going to make this the worst day of your life", and then proceeded to do his best to achieve that end for the next six months. Ironically, his name was Mr. Angel. He proved to be anything but.
I've dealt with clients who want the impossible (and always want it immediately, if not sooner) and then found myself on the end of completely scathing reviews when they are (unreasonably) dissatisfied. Your client will probably do the same to you. In today's on line based market, there's nothing much you can do about one bad review. If there is only the one bad review, most reasonable people will understand the issues of unreasonable demands.
Look at the one star reviews of cameras. There will always be the person who gives the lowest grade to a product because they felt it was too difficult to, say, thread a UV filter onto the front of the lens. So the entire camera gets downgraded. We all see that as irrational and not the fault of the camera manufacturer. You have to do the same with your own on line reviews. They are what they are.
Most people I've known who have made a career of working with the public enjoy their job because no two clients are exactly the same. The best you can do at this point is forget this incident if you are convinced you were not at fault. There will be more like this client if you stay in this field. And there will be clients who make your job a true pleasure. Until the former begins to outnumber the latter, you have to eat your broccoli too.
