A million reasons why : a novel / Jessica Strawser.

"When two strangers are linked by a mail-in DNA test, it's an answered prayer-that is, for one half-sister. For the other, it will dismantle everything she knows to be true. But as they step into the unfamiliar realm of sisterhood, the roles will reverse in ways no one could have foreseen. Caroline lives a full, happy life-thriving career, three feisty children, enviable marriage, and a close-knit extended family. She couldn't have scripted it better. Except for one thing: She's about to discover her fundamental beliefs about them all are wrong. Sela lives a life in shades of gray, suffering from irreversible kidney failure. Her marriage crumbled in the wake of her illness. Her beloved mother and lifelong best friend passed away. She refuses to be defined by her grief, but still, she worries about what will happen to her two-year-old son if she doesn't find a donor match in time. She's the only one who knows Caroline is her half-sister. That Caroline may be her best hope for a future. But Sela's world isn't as clear-cut as it appears-and one misstep could destroy it all. After all, would you risk everything to save the life of the person who turned yours upside down? From the moment Caroline meets Sela, both must reexamine what it really means to be family, the depths of a mother's love, and the limits and the power of forgiveness"-- Provided by publisher.