"I’m thirty-four, you know. I’m not going to be one of those bitches that ruins children." (19.49)
Brett’s affair with Romero (who’s only nineteen) has forced her to confront her conscience for the first time – yes, she actually has one! Her obsessive wondering in the last two chapters about whether or not she is a "bitch" reaches its culmination here, where she has apparently made up her mind not to be one.