Delusion or Confusion?

What is it Delusion or confusion? Is a fantasy book written from a point of view of a young girl named Clara she is 9 years old, Clara is scared her father is always upset with her, for a reason she can't do anything about. And that reason is, she sees things others don't like her best friend Lucy. But when family secrets reveal she learns all about what she actually is and why these weird things are happening.