Inside Hugh Hefner and Holly Madison’s Strained Relationship: From 'No. 1 Girl' to Estranged Exes

Family, friends and fans are mourning the loss of Hugh Hefner, the Playboy founder who died peacefully at his home at the age of 91 on Wednesday.

While many of his famous Playmates have expressed their condolences via social media and in statements to ET -- like Kendra Wilkinson, Bridget Marquardt and Pamela Anderson -- there's one that's been noticeably silent: Holly Madison.

From 2002-2008, the platinum blond beauty was Hefner's "No. 1" girlfriend. But according to Madison, all of that went downhill... and fast. In her 2015 memoir, Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny, Madison claims she contemplated suicide due to her unhappy life in the mansion.

From head over heels to their now-infamous feud, ET's breaking down what led to their strained relationship, and how it affected Madison's friendship with one of her The Girls Next Door co-stars.

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August 2001: Madison moves into the Playboy mansion

The Astoria, Oregon, native, now 37, officially became one of Hefner's girlfriends after moving to Los Angeles, modeling for Hawaiian Tropic and working as a waitress at Hooters. It was through these jobs that she received her first invitation to the mansion, where she met Hefner for the first time.

2002: Madison reveals she'd love to marry Hefner

The model, who quickly became Hef's "No. 1 Girl," made it clear from the beginning that her heart only belonged to Hefner. In multiple interviews, Madison stated that she wanted to tie the knot with the Playboy mogul and have his children.

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May 2008: Hefner breaks Madison's heart, explains why she'll never be his wife

At a Playmate of the Year luncheon held at the Playboy Mansion, Madison told reporters that she and Hefner were "no closer to getting married than we were years ago" and that their relationship was like "a car stalled at the side of the road."

Hefner chimed in, saying, "I love Holly very much and I think we're going to be together the rest of my life, but marriage isn't part of my puzzle. It's not a personal thing; I just haven't had much luck with marriages."

Fox News reported at the time that Madison "sadly turned away" while Hefner spoke. The magazine publisher was previously married to Millie Williams (1949-1959) and Kimberley Conrad (1989-2010). He later married Crystal Harris in 2012.

October 2008: Madison and Hefner call it quits

In an interview with the Associated Press, Hefner confirmed he and Madison broke up. He revealed that the split came about six months after he told her he wasn't interested in getting married or having anymore children.

"If Holly says it’s over, I guess it’s over," Hefner, seemingly heartbroken over the split, said at the time. "She's still here in the house. Until a few days ago, we were still sharing the same bed."

"The fact that she was depressed after that, I didn't know at all," he added. "That was a revelation in the last days and weeks. Quite frankly, we thought when the time came, we would make a combined statement and we expected that combined statement would be somewhere in the weeks and months ahead."

September 2013: Madison marries Pasquale Rotella

Despite saying in a 2009 interview that she was "never dating anyone again" -- "I don't need a man. I'm really happy with myself and being with my friends" -- Madison started dating Pasquale Rotella in 2011. They welcomed their first child together, daughter Rainbow, in March 2013 and said "I do" at Disneyland in September of that same year. The two welcomed their second child, son Forest, last August.

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June 2015: Madison releases first memoir, slams Hefner and life in the Mansion

Titled Down the Rabbit Hole: Curious Adventures and Cautionary Tales of a Former Playboy Bunny, Madison detailed all the highs and lows of living in the Playboy Mansion. She claims she was subjected to a myriad of house rules, and was verbally and emotionally abused by Hefner, which led to depression and thoughts of suicide. Madison also claims that Hefner was a "manipulator" and "pitted" many of the Bunnies against each other.

"If I just put my head under water and take a deep breath in, it would all be over," she wrote in her tell-all, recalling a suicidal moment she had in the bathtub. "Drowning myself seemed like the logical way to escape the ridiculous life I was leading."

Madison also claimed that Hefner tried to bribe her from moving out of the Mansion by writing her into his will as one last desperate tactic to save their relationship.

"It was there, in black and white," she wrote. "The will stated that $3,000,000 would be bestowed to Holly Madison at the time of his death (provided I still lived in the Mansion). At the time, it was more money than I'd ever know what to do with… But I didn't want it. I actually pitied him for stooping to that level. I couldn't help but be offended. Did he really think he could buy me? I put the folder back on the bed just as I had found it and never breathed a word of it."

June 2015: Hefner denies Madison's allegations

Following the release of the book, Hefner exclusively told ET that Madison "decided to rewrite history in an attempt to stay in the spotlight."

But Madison quickly fired back, telling ET,  "It wasn't about having an ax to grind or wanting to get a reaction from him, or, you know, inviting him back into my life in any way.”

"I don't really care about his response," she continued. "I wanted to share my story to inspire other women who might be in a bad relationship to get out, or not be branded by bad decisions they've made, and take charge of their lives and move on. ... I'm definitely not rewriting history. I'm finally telling the truth of my experience. For so many years I tried so hard to be a good girlfriend, and I cared about him and always had his back."

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Summer 2015: Wilkinson furious with Madison's memoir

After Madison wrote in her tell-all that Wilkinson was "the fakest person I've ever met," a feud between the girls quickly started brewing. Wilkinson responded by claiming the entire memoir was a lie.

"Holly, you can tell, had this ulterior motive every minute being at the Mansion, and that motive was – it was clear as day – she wanted Hef's kids, she wanted a piece of Playboy and she wanted to marry Hef for, obviously, his will," Wilkinson said in an interview with People at the time. "That didn’t happen. So what do you think's going to happen? Revenge. So we're witnessing some revenge here."

"How could [Holly] want kids and [to] get married to him and then, next thing you know, say these types of things about Hef?" she added. "It’s just out of revenge, and I feel bad for Hef. But you know what? He’s an amazing human being."

Wilkinson also addressed Madison's book on her reality show, Kendra on Top.

"What Holly is saying is extremely false," Kendra claimed. "I'm like, 'Where did this s**t come from?' Someone needs to have a voice against this. Hef won't do it. He's too nice of a guy. It's just weird how someone can get away with such a thing."

Summer 2016: The feud continues

Nearly a year after the release of Madison's tell-all, Wilkinson said in an interview with SiriusXM satellite radio's Morning Men with Evan Cohen and Mike Babchik that she was still on Hefner's side.

"I'm protecting [Hugh Hefner], I'm protecting myself, I'm protecting the things that actually made us famous," she explained. "I'm very appreciative, and I'm very loyal and he did no wrong. He did no wrong to anyone, and if he did, you know, I would be here telling you. If I felt for once that he treated us unkind in any way, I would be here defending Holly. But I'm not."

The interview came a few days after Wilkinson slammed the comments Madison made in a different interview about feeling "a lot of fear" in the Mansion.

"She wasn't in fear with that d**k in her a** for a paycheck," Wilkinson tweeted.

"I want no part of a one-sided argument or feud where one woman lives to demoralize and degrade another woman," Madison responded in a statement to ET. "For those with unresolved issues, therapy works. You should try it."

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May 2016: Madison gives ET an update on where her relationship with Hefner stands

When Madison stopped by ET for an interview to promote her second memoir, The Vegas Diaries: Romance, Rolling the Dice and the Road to Reinvention, we asked her what she would say to Hefner today if she could.

"I wouldn't say anything," she revealed. "And I think it's interesting because people will ask me all the time, 'Do you still talk to him?' Usually when people move on, they don't talk to all their exes. I just don't think it's appropriate."

"Of course I have fond memories of my time there, but, you know, you move on.. do other things," she added. "I would say my best memory of the time at the Mansion was shooting the TV show. It provided us with a lot of opportunities and we got to travel because of it, try new things. We had fun doing that."

September 2017: Hefner dies at age 91

Madison has yet to break her silence on his death. ET has reached out to her reps for comment.