Newlywed and pregnant singer Kelly Clarkson shot down rumors that her husband, Brandon Blackstock, cheated on her.

An anonymous woman wrote a letter to claiming she has been cheating with Blackstock for the past five months. The note was published on Monday, Dec. 2.

"Brandon has been cheating on Kelly (with me) for the past 5 months," the unidentified woman wrote. "We met at a golf club in TN and have exchanged multiple texts and hung out a few times over the last little while. Because his parents are music royalty, Brandon really thinks he is invincible and better than everyone else. I don't even know why I'm saying any of this since my story isn't that juicy."

The woman claimed she has been intimate with Blackstock but they have not consummated their secret affair.

"We haven't slept together but we've been intimate in other ways," she revealed. "I really hope his wife keeps her eye on him because he's not the great man that she thinks he is."

The mystery woman explained in the beginning of her letter why she chose to not reveal her identity, saying she hopes to keep at least that private.

"I like the idea of keeping myself anonymous, whereas any other media outlet would have jumped at publishing my name," she explained. "I have a career and children to keep safe, so your site was my best option."

Radar Online reported on Thursday that one commenter who responded to the letter claimed to be Clarkson. The writer said her former assistant wrote the letter, and the commenter said the report of an extramarital affair with Blackstock is "absurd."

"This is absolutely absurd," the comment rumored to be written by Clarkson read. "The woman who posted this fictitious rumor about my husband use [sic] to be my personal assistant until I terminated her for trying to steal from me. She even tried to impersonate me by soliciting funds using my name and created a ficticious website. This woman is just out for revenge."

A rep for Clarkson told the gossip website "We do not comment on our artists' personal lives." 

Brandon's ex-wife, Melissa Ashworth, called the claims about him "ridiculous" and referred to them as "silliness."

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Clarkson announced her marriage to Blackstock via Twitter on Oct. 21, saying they tied the knot the day before. Blackstock is the son of famed music manager Narvel Blackstock, who manages Clarkson. His stepmother is country legend Reba McEntire. The Stronger singer later revealed her pregnancy on the same social media network on Nov. 19. She described the news as the "best early Christmas present ever."

"I'm pregnant!!! Brandon and I are so excited!"

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Clarkson will appear in her own Christmas special, Kelly Clarkson's Cautionary Christmas Tale, on Dec. 11.  The comedic story shows her learning the true meaning of Christmas, accompanied by the music from her Wrapped In Red album.

Kelly Clarkson's Cautionary Christmas Tale will air Dec. 11 at 10 p.m. EST on NBC.