I might consider chapter 12 when Lily comes to terms with her relationship with herself. August tells Lily that her self-loathing and guilt are needlessly crushing her. Lily blames herself for accidentally shooting her mother. August is suspect of this but still says:
But you're not unlovable. Even if you did accidentally kill her, you are still the most dear, most lovable girl I know. Why, Rosaleen love you. May loved you. It doesn't take a wizard to see Zach loves you. And every one of the Daughters loves you.
Lily discovers that she is indeed lovable and has so much to give. Lily need not be defined by her past.