What does Song witness to cause her to decide "that this was the last time she would feel so impotent against evil"? What difficult and powerful decision does she make in response?

Sometimes it is the most devastating moments that move us to act. What does Song witness to cause her to decide "that this was the last time she would feel so impotent against evil" (61)? What difficult and powerful decision does she make in response?

Song was forced to witness the disposal of a young, pregnant woman's body; a beautiful courtesan who became "inconvenient" and posed a danger in family lineage. She vowed to take care of herself, to conceal her true being and to take advantage of rare opportunities such as the chance revealing of her elderly, senile charge's cache of diamonds.

The murder of a pregnant mistress posing a threat to the family. Song vows to take care of herself, keep her authenticity under wraps, her 'wealth' a secret. Self empowerment.