The Heat of The Moon by Sandra Parshall

When Dr. Rachel Goddard is overwhelmed by disturbing visions of a childhood trauma, she turns to her family for help. But her sister doesn't remember the terrifying scene that Rachel can't forget. Her psychologist mother's elegant reticence and logical explanations seem to make sense ... until one unexpected discovery shatters everything Rachel thought she knew. Now with her sanity and future at stake, Rachel finds every memory suspect, each new clue a land mine and any safe haven dangerously false. And as wrenching secrets put her at odds with a family she can't protect or trust, she walks the knife edge between lies, illusions, madness and a shattering revelation that could cost her everything.