The Almost Moon by Alice Sebold

When all is said and done, killing my mother came easily.
A woman steps over the line into the unthinkable in this brilliant, powerful and unforgettable novel by the author of The Lovely Bones.
For years, Helen Knightly has given her life to others: to her haunted mother, to her enigmatic father, to her husband and now-grown daughters. When she finally crosses a terrible boundary, her life comes rushing in at her in a way she never could have imagined.
Unfolding over twenty-four hours, The Almost Moon explores the ties between mothers and daughters, wives and lovers, the meaning of devotion and the line between love and hate. It is a challenging, moving, gripping story, written with the humanity and fluidity that only Alice Sebold can bring to the page.