Late bloomer - Fern Michaels

Thirty-year-old Cady Jordan, who's lived her adult life cautiously and predictably, is going home to Indigo Valley, Pennsylvania, to care for her ailing grandmother. And, boy, is she nervous. It's not just that change of any kind sets her teeth on edge, it's because she's going back to the town where the tragedy that has shaped her life took place. When she was ten years old she and a group of friends as well as a couple of bullies were climbing a tree, and when the play got rough, Cady and one of the bad guys fell out of the tree. She hit her head, fell into a coma and underwent years of physical therapy before she recovered, but the boy died, and everyone blamed her for his death.
When Cady, who has no memory of the accident, returns to Indigo Valley she reconnects with her old friends, some of whom witnessed the tragedy but never admitted it. With her eccentric but loving grandmother's support, she attempts to recover her memory of that momentous day so she can shed all of the guilt and bad feelings that have been crushing her spirit. Along the road to discovery, she gets involved romantically with the town's police chief who was one of the bullies involved in the tragic incident.