Why does Liesel angrily shout at Frau Hermann in the library of her house?

Frau Hermann finally convinces Liesel to take a copy of the book "The Whistler". At the same time, she hands Liesel a note explaining that she has to fire Rosa from her laundry service. Liesel hurls the book back at Frau Hermann and begins shouting that Frau Hermann is a pathetic old woman who hasn't been able to get over the death of her son.