What is revealed of Cheryl's past in the flashback to the Mayo Clinic in Chapter 1: “The Ten Thousand Things”?

Cheryl takes the reader back several years to when she was in the Mayo Clinic with her mother and step-father, Eddie. Cheryl remained in denial about her mother's diagnosis until the doctor stated that her mother had late-stage lung cancer, that treatment would not help and that their focus would be pain relief.