I agree with Nicky about speaking to the director, and document it in writing.
If it were me, I would have to make my decision about staying there based on what was agreed to at the meeting, and whether or not the director can assure you that things like that will not happen again.
I would make an appointment, and make it with just the 3 of you (2 moms and director). Make it clear that there was a serious problem, that you want an immediate appointment, and that the problem is serious enough for you to consider other arrangements for your daughter.
Depending on the outcome of that meeting, if you would choose to keep the twinkle there, I would make sure to put into writing all agreements as you understand them, and ask for her written agreement to them.
This is your child. You have every right to demand appropriate behavior.
cris - grandma to 13