Stuck in Create a Sim/Create a Household

I'm playing The Sims 3 - Pets. I bought a foal from the shelter, and after he grew up, I wanted to customize his saddle. So the game enters Create a Household, and I begin changing some colors on the saddle and bridle. At some point I want to drag a color to another accessory, but I accidently drag it onto my horse/horse's coat. Then the game sort of freaks out, and I'm unable to do anything.

This is a screenshot of the current situation

There's an alert message saying "The current style is invalid. Please select a new style before continuing."

The arrow points at the custom content icon, but if I click it, nothing comes in. When I click it again, the image that can be seen in the screenshot comes back. However, even if I click it or double click it, nothing happens. I can't save, and I would lose so much progress if I just quit...

Otherwise I tried clicking everything once, twice, with the right mouse button, middle mouse button, but nothing works. I tried using the console, but I didn't find anything useful that could help me. I tried searching for this problem on the Internet, but nobody has encountered this problem as far as I know.

I've been using custom content and colors for a while now, and it has never been a trouble before, even though a hint suggested some players to try playing without custom content to fix problems.

I don't know what to do, this has never happened before, and I just can't believe that it's the custom content's fault.

Obviously the game thought I meant to apply the color to the coat, maybe the pattern, too. But there's no undo button, so I can't go around this problem.

Can someone help?