Some advice, for anyone who's prone to finding themselves in a similar situation, starting with the most general:
Have a backup plan.
Thankfully, past me did a good job preparing for exactly such a situation. I have insurance on my equipment, and savings set aside for exactly this kind of emergency. If all of that fails, I have credit and family to fall back on. If I needed to replace the equipment immediately, I have a list of local places at which I could buy, rent, or borrow equipment.
So, business wise, I'm okay. Knowing that was a huge comfort while literally picking up pieces of my camera.
Even if you don't own a business, it's a good idea to take some time and think about where you are most vulnerable to an accident, and figure out how you can mitigate that risk.
Don't ignore that bad feeling in your gut.
My tripod hadn't felt right all morning. I don't use my tripod often, though, and it seemed to be working, so I carried on. I've since worked out that a key spring in the tripod head had come lose. It's an easy fix, but a critical failure.
First of all, if your tripod feels weird, you should have a hand on your camera constantly until you figure out the problem, and should not use the tripod until it is working correctly.
But more broadly, when something feels wrong, you should always stop and try to assess that feeling.