I'm with the majority here. You did the right thing. Really, the only thing.
When I'm doing something "iffy" ... and I do this quite a bit as one might imagine
... I figure out the risk/reward aspect of it.
Doesn't seem like getting caught by family and/or friends, to get some strange, would be worth the fallout if (and this is a huge if) you had gotten caught.
If this was a last minute cancellation, though, doing something a little sweet for the person that you stood up would have been nice ... even if it was just sending her a little something from her Amazon wishlist (an example, only).
But I bet she understands why you cancelled, either way.
Best,
Elisabeth