Personally, I would 'out' her.

My husband just sold a bike on ebay last week and a day later regretted his decision. He really, really, really wanted to back out (even considered telling the buyer it was stolen!), but knew that he'd made a deal and had to go through with it. He shipped it this morning and probably had tears in his eyes when he did.

It's too bad for her that she didn't read all the rules. They are all there, in black and white. AND, if she really did make a mistake in her listing, she didn't have to let it complete before changing her mind. As long as there are no bids, you can change or retract your listing.

Ignorance is no excuse. She should have honored her commitment and you have every right to share your experience with others.