Hopefully she didn't have it in her long enough to do any damage.
I've had to induce vomiting before. My son left a "Sugar Free Tic-Tac" container laying on his floor. Reno came carrying it in to me - EMPTY - and he had chewed the label off so I couldn't tell if they contained Xylitol or not. I gave him peroxide to make him get sick....let me tell you - it works!
Poor Reno - turns out, the Tic Tacs don't contain Xylitol, but I couldn't take the chance that they did. To make matters worse, my son told me the container had been empty already
Keep us updated know how Willow is doing.