The original question had to be edited down.  I invite you to resubmit the different parts as individual questions.  I think that the resolution in Anderson's work is one of acceptance.  Lia recognizes that her own self- perception is causing irrevocable hurt and pain to her own being. She understands that the self- destructive pattern in which her cutting and starvation is leading her.  It is one that compels Lia to accept that she needs help.   The work resolves with Lia understanding that she gains nothing from emulating Cassie's own self- destructive devolution.  Lia understands that the road to wellness is a challenging one.  Yet, in making the commitment to walk it, she has already moved past where Cassie could never reach.  Lia reaches out for help before it is too late.  In this, she demonstrates herself to be different than Cassie.  It is a resolution in which there is hope, but it is a gritty one.  It is an ending where one fully understands that there is no such thing as "cured" for Lia.  Rather, it is a movement one day, one hour, at a time towards a state of being that is not so wrought with personal destruction and self- hate. It is here where the book's resolution lies.