Showing Breathless by Jessica Warman

When Katie Kitrell is shipped off to boarding school by her distant father and overbearing mother, it doesn't take her long to become part of the It Crowd. She's smart, she's cute, and she's an Olympic-bound swimmer who has a first class ticket to any Ivy League school of her choice. But what her new friends, roommate, and boyfriend don't know is that Katie is swimming away from her past, and from the schizophrenic older brother, Will, who won't let her go. As Katie's star rises, her brother descends deeper into insanity. And when he does the unthinkable, it's all Katie can do to keep her head above water.