The Museum of Extraordinary Things by Alice Hoffman
The Museum of Extraordinary Things is about Coralee whose father owns a freak show in Coney Island. At first Coralee doesn’t realize that her father is a narcissistic sociopath because she is too young to see. When the freak show starts to become irrelevant, he makes Coralle become a part of it by pretending to be a mermaid because she was born with webbing between her fingers. It becomes apparent that he has been grooming her to play this part for most of her life and once the freak show and her mermaid act start to lose popularity, her father makes her do things that go against her morality.
Eventually she becomes enlightened with the help of some of the people around her and goes against her father and things come crashing down. In the end good wins over evil.