Explaining
In the end, Crystal told her mother the reason she skipped town. It turns out that she had been suffering sexual abuse at the hands of a neighbor. This started when she was no more than 9 years old and kept happening for years. Back then, it happened so frequently that she did not think it was unusual.
Unbelievable
This was the first time that Cynthia had ever heard about it. It was shocking to hear that this terrible thing had been happening to Crystal, yet she had no idea. All this time, Crystal assumed that her mother knew what was going on. However, the truth was that she was not aware of it at all.