Screenwriter Kelly Marcel, who wrote Fifty Shades of Grey, says she will not watch the film as she feels cheated by the filmmakers.
The 41-year-old writer, who also wrote the 2013 film Saving Mr Banks, said the movie will be too "painful to watch" as the makers promised her "utter, utter nonsense", said The Hollywood Reporter.
"I wanted to do something different with the screenplay, and when I spoke to the studio and the producers and made that quite clear, they were very enthusiastic about that and loved the things I wanted to do," Marcel said.
"When I delivered that script I realised that all of them were saying, 'Yeah, absolutely this is what we want!' and, 'You can write anything you like and get crazy and artistic with it' — that was utter, utter nonsense."
The screenwriter said she will not be able to view the film "without feeling some pain about how different it is to what I initially wrote."
"My heart really was broken by that process, I really mean it," she added.
The film, adaptation of author EL James' erotic novel of the same name, was a huge hit upon its February release, with a follow-up on the way.