Holly Madison is still promoting her book "Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny." According to a report from Life and Style, the "Girls Next Door" star slammed Hugh Hefner's wife after feuding with former co-star Kendra Wilkinson.

The 35-year-old TV personality warned 29-year-old Crystal Harris, whom Playboy founder Hugh Hefner married on December 2012.

"You are definitely getting in over your head," Holly Madison told Crystal Harris. "I thought being a live-in girlfriend would be a light, fun thing, but it was a lot heavier."

Holly Madison's book revealed a lot of secrets from her seven-year stay inside the Playboy mansion. Known as Hugh Hefner's "Number One Girlfriend," she explained how the 89-year-old magazine mogul was very controlling.

"He made me give up my last shred of independence," Holly Madison said.

"We weren't allowed to have outside jobs, and it was so catty among all the girls."

"Crystal's in the same situation I was, which is really hard for someone in her 20s. It's way more intense than you could imagine," she added.

Aside from addressing Hugh Hefner's wife, Holly Madison's publicity for her book has caused a major fight between her and Kendra Wilkinson.

People reported how Kendra Wilkinson criticized Holly Madison's tell-all book, which revealed the alleged rampant drug use inside the Playboy mansion, detailed Hugh Hefner's manipulative tactics and labelled Kendra Wilkinson as fake.

"It's pretty sad," the "Kendra on Top" star said about Holly Madison's book.

"It makes you question the timing, and it makes you wonder, 'Wow, she wants real revenge.'"

"At the end of the day, true colors shine," the 30-year-old reality star added.

Kendra Wilkinson also accused Holly Madison of being vengeful because Hugh Hefner did not marry her.

"The one thing she truly wanted was a piece of that stock, a piece of Playboy and a piece of Hef's will," Kendra Wilkinson pointed out.

"She considers herself a failure because she did whatever it took to get that and she didn't get what she wanted in return."