The correct answer to this open question is the following.
Charity was affected when Mistress Bradstreet revealed that she also writes poetry in the following way: Charity was surprised to know that Mistress Bradstreet wrote poetry too. The text says that "Charity's jaw dropped." Indeed, Mistress Bradstreet had also published a book. She told Charity that she always was writing poems. This activity distracted her from her daily routine.