The 30-year-old reality star revealed as much in an interview with People following Madison's unflattering portrait of her and mutual ex Hugh Hefner in new memoir Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny.
"I don't ever want to have a relationship with Holly again," Wilkinson declared. "And I made a mistake by thinking what we had was real. A lot of stuff was done out of like, 'Oh, we gotta stick together to make this certain image last,' but then I realized I am a different person, I have a different lifestyle."
Wilkinson and Madison simultaneously dated the 89-year-old Playboy founder from 2004 to 2008. The pair were close enough in the past for the reality star to have Madison and fellow former girlfriend Bridget Marquardt as bridesmaids in her wedding to Hank Baskett in 2009.
"The last thing I want is for whatever she does in her life to affect my life," Wilkinson said of her former friend's tell-all book, released Tuesday. "We aren't sisters, we never were. We just dated the same guy at the same damn time."
Wilkinson defended Hefner against Madison's allegations earlier this week, telling People the television personality wrote the memoir for "revenge." Madison claimed she wrote the book "to tell [her] story and hopefully inspire other women" during an appearance on The Wendy Williams Show on Wednesday.