In the book her father explicitly never actually abused her - there was a moment where he* demanded to know if Bev had been slutting around, and wanted to see if she was "intact".
When she was an adult IT took the form of ZombieDad and he creeped her out by saying he wanted to abuse her, but never did.
Her mum was also alive in the book, unlike both film versions. At one point she asked Bev if her dad had ever touched her, but he hadn't and the question confused her.
* at the time he was either really drunk, crazed by anger, influenced by IT, or actually a form of IT