Three of Hugh Hefner's former girlfriends -- Holly Madison, Bridget Marquardt and Kendra Wilkinson -- are at odds after Madison slammed Wilkinson in her new memoir, "Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny," Inquisitr reports.

Despite the fun antics between the women depicted on the E! reality televisions series, "The Girls Next Door," that aired 2006-2010, Madison's new memoir suggests they did not get along well at the Playboy mansion, and she blames Wilkinson. She describes the "Kendra on Top" star as "the fakest person [she has] ever met."

The memoir's excerpts reveal that Madison has deep disdain for Wilkinson.

"Kendra had apparently given an interview to a tabloid explaining that she wasn't friends with either of us [herself and Bridget Marquardt] as if she were somehow better than everyone else. ... Of course I wasn't going to stoop to her level and address this only on social media, so I decided to text her how I truly felt: that she was a coward and that she tried to act like the 'real' girl on TV, but she's the fakest person I've ever met -- and that if she had a problem with me, she should have confronted me like an adult instead of just going silent," Madison said in the book. "After that, I deleted her number from my phone. Kendra and I haven't spoken since, and I have to say, I don't miss her."

Madison also calls out Wilkinson as a liar for something she wrote in her memoir.

Wilkinson's book, "Sliding Into Home," mentions that Hefner gave her a house key and asked her to be his girlfriend before she ever went to his bedroom. But Madison says this is not true at all.

"Now, I don't know if Kendra is trying to sound extra-desirable, innocent, or if her memory is just super rusty, but of course that's not how it really went down," she said in the book. "Hef isn't stupid. He never asked anyone to become a girlfriend before they joined him in bed. And he never made a habit of carrying around extra sets of room keys."

Madison's memoir also accuses Wilkinson of lying to Hefner about her former job as a stripper.

Marquardt showed her support for Madison by posting a throwback photo of herself with Madison on social media, which Madison retweeted on Twitter.

The 2008 photo was taken when the trio starred in the "Girls Next Door" episode in which the three women partied in New Orleans for Mardi Gras.

Wilkinson has not commented on the accusations.

Once the "Girls Next Door" TV series ended in 2010, the three women left the Playboy mansion, and Hefner started dating playmate Crystal Hefner, whom he married in early 2013.