Good luck tonight!! Stay strong and let them know that if they don't pay, you will have to take them to small claims over an unpaid bill. (even if you don't, I would threaten too lol)

I know you probably just wanted to vent but I also suggest that you request payment ahead of time. I do 2 weeks at a time but if yours is a month, then charge a month ahead. It will save you time, stress and headaches in the future. I would change this asap for all families in your care now.