Lily is a good liar. This helps, but at a cost. How does it help and what is the cost

I don't think we can condemn Lily so much for lying. Her past was filled with abuse and she has found stability and refuge at Boatwrights. Lily does what she thinks she needs to in order to be accepted. Lily tells the Boatwrights that both of her parents have died and that she was left without any family. She says that Rosaleen was the family housekeeper and that the two of them are on their way to Virginia to stay with Lily’s aunt.  Lily can sense that August can see through her lies and that August knows much more than she is revealing. Such moments of understanding allow Lily to recognize her prejudice, and later she will be able to cast it aside.