Sharon Osbourne hits back at brother's 'devastating' X-posé

But back then Sharon Osbourne had a little more editorial control over the secrets revealed.

Now, in an astonishing attack on his younger sister, Sharon Osbourne's brother David has blown the lid on her supposed "gossiping" ways and revealed how she apparently attempted to sabotage the last series of X-Factor when it was clear she wouldn't win.

In a five-page X-posé in the News of the World he details a string of damaging revelations in an attempt to ruin the X-Factor judge's celebrity friendships and her role on the ITV show.

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He said she had tried to persuade X-Factor hopeful Ben Mills to quit the show before the final when it was clear Leona Lewis was going to win, because she couldn't bear to lose out to Simon Cowell again.

According to David Arden, 56, she hates Simon Cowell off-, as well as on-camera.

He said: "Sharon absolutely loathes Simon Cowell. She's told me she thinks he's an 'arrogant and extraordinarily pompous know-it-all and egomaniac'. But most of all she resents his success. Sharon can't stand anyone being more successful than her.

"Another thorn in her side is Simon is the star of the X Factor when she thinks SHE should be the undisputed centre of attention.

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"Sharon always goes for the jugular with her enemies. And that's what she sees Simon as, despite all he's done to restart her career after her US chat show flopped.

He added: "Outrageously she tells everyone he's gay. She claims he's 'in the closet' and doesn't yet know he's homosexual, which is ridiculous."

David expects Sharon's days as an X-Factor judge are numbered.

He said: "Sharon will hate Dannii. She's always had a problem with women who are better-looking than her. Already Dannii's stolen Sharon's thunder and the talking points have centred around the new girl and the return of Louis. Sharon is nowhere to be seen.

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"Even on the official PR photos she's been shoved to the back. That will annoy her extremely. Dannii's been such a hit it makes it easier for Sharon to be dropped. Simon must be aware of her feelings and what happened with Ben last time around.

He concluded: "Sharon's days are numbered. And it's all down to her own appalling behaviour."

According to David, she has also betrayed friends Elton John and Sarah Ferguson by gossiping about their most intimate secrets.

The siblings became estranged in July after a row over where their father, Don Arden, should be buried.

He also accuses her of taunting her own daughter, Aimee, by inviting David Walliams over for dinner when he had just broken off a relationship with her.

He says she is often bad-mouthing other stars including Madonna, of whom Sharon apparently said: "She is disgusting for trying to buy a baby."

And he says she can't stand "footballers and their cheap little wives" and finds Sting and his wife Trudi Styler "disrespectful and snooty".

Now he has almost certainly burnt bridges forever with his sister. She has responded to the accusations by saying she is "devastated and disappointed".

But friends say she will not let him get away with his betrayal, and is planning her revenge in the second part of her autobiography, due out in October. This latest episode of The Osbournes looks set to run and run.