According to new unauthorised biography, 'Sweet Revenge: The Intimate Life of Simon Cowell', the 59-year-old matriarch ''exploded'' with rage upon learning that Simon was sleeping with Dannii Minogue when they all worked on the UK 'x factor'.
Now the matriarch - who eventually quit the show in 2008 because she no longer wanted to work with Dannii - has taken aim at her old boss from involving her in his ''world of debauchery''.
She said: ''I'm not Simon's mother - I don't give a toss who he f***s.
''That's none of my business. I think Simon thought he'd have complete control over this book.
''But how dare he bring me into it now? I don't want to be dragged into his little world of debauchery, thank you very much.
''I get on absolutely fine with Simon - and he will be fine - but I am p***ed off to be brought into it all again.''
Her rows with Dannii became notorious, although Sharon argues they had nothing to do with Dannii's reported romance with Simon.
She told the Daily Mirror: ''Dannii wanted to be the mistress of Simon Cowell - and the mistress of 'X Factor'.
''But I didn't leave the show because Simon and Dannii were f***ing, I left because she became unbearable. She started bossing everyone around, even the producers.
''We all knew Simon and Dannii were seeing each other, it wasn't a secret. I don't know why he tried to hide it from everyone though.''