The 29-year-old 'Call my Name' hitmaker was stunned to be told by Richard Holloway, the show's executive producer, that the music mogul criticised her big hair and the orange shirt and purple trousers she wore for the first day of auditions.
She was also told that he wanted her off the US version of the programme, and she was particularly angry that her friend didn't break the news himself, reported Sun online.
In her autobiography 'Cheryl: My Story', she wrote, "I was furious with Simon for letting it happen like this. I believed we had a good friendship and couldn't understand why he hadn't been straight with me.
"I wrote the longest text ever. 'I hate you. I understand you're a businessman, and what I've learned from this is business means more to you than friendship. I'm sad it's got like this and I wish you the best of luck, but count me out'," she added.
"Simon texted back, 'Can I talk to you?' I ignored him."
