As soon as I was told to address anything further with her husband, and to not "poke the lion", I would have terminated. This is completely disrespectful and immature behaviour. I am afraid that I would NOT accommodate anyone who expects their kid not to get dirty, nor would I tolerate someone shutting me down when I have issues to discuss with regard to the care of THEIR CHILD.

Seriously - how childish of her.

I would word it thusly,

"in light of our recent difficulties and your , it has become clear that refusal to discuss and resolve any issues, it has become clear to me that I can no longer accommodate the expectations of your family. Please have this notice serve as your two weeks notice. As of Sept 12, I am no longer willing to provide care for your son. I wish you luck finding a daycare provider more suitable to your needs.

Thank you,

Littledragon