Family (Firstborn #4) by Karen Kingsbury

In the wake of finding his firstborn son, John Baxter looks for a way to tell his other children the truth about a secret he's kept from them all their lives. At the same time, a sensational Hollywood trial brings Dayne Matthews and Katy Hart together again, this time in a very public way. Just when love might have the chance to win, doubts and presumed scandals place them farther apart than ever. In the midst of this crisis, the truth is clear for all of them—never in their lives has family been more important.