Four days before the shock announcement of her death at age 80 on Tuesday, country music's long-reigning queen Dolly Parton had given fans one final glimpse behind the rhinestones.In a short interview with People magazine, the singer admitted that the strain had been taking a toll. Her husband, Carl Dean, had died in March last year at age 82 and, after nearly 60 years of marriage, the loss had sent Parton into a protracted period of solitary grief.'I am dealing with some health issues that I just didn't pay attention to when I was watching over Carl,' she told People on Friday.The star's pain had been compounded in July this year when her older brother, Coy 'Denver' Parton, also passed.But even as she briefly acknowledged the difficult year she had endured, those close to the singer say she had both became increasingly reclusive and secretive about her own ill health in recent months.Insiders say Parton had all but retreated behind the gates of her sprawling Tennessee compound, allowing the details of her worsening sickness only to be known by an exceptionally tight circle of friends and family.Indeed, she even went as far as to dismiss concerns about her health during the People magazine interview last week. 'It’s not like I haven't been through hard times with my health,' she said. 'I’m still healin’, I’m still workin’.'But now, insiders have told the Daily Mail for the first time just how sick Parton had been in her final months.'Her health problems were much worse than she was willing to tell fans, obviously, and she was bad off for many months,' one source said. 'She didn't want the world to know that she was very sick.'Insiders tell the Daily Mail that Dolly Parton concealed just how sick she had become in her final months; Above, in 2005 'She publicly tried to blame her illness on how she let herself go after Carl [Dean] passed last year,' a source told the Daily Mail'Dolly only confided in a very small, intimate circle what she was going through,' said another insider.'She publicly tried to blame her illness on how she let herself go after Carl passed last year. It's true his death took its toll severely on Dolly, but she's been sick and receiving treatments for months.'Parton was admitted to a Nashville hospital on Friday and, late on Tuesday, her team confirmed that she had succumbed after a 'brief battle' with cancer.Indomitably glamorous, the country superstar never wanted her adoring fans to see her fade.'When Dolly told People [magazine] she was still working and healing, she knew her life was almost over,' one source said.'She tried to reassure her legions of fans that she wasn't critically ill. But she knew her time was almost up. She was being her brave Dolly self, not wanting to let her fans down.'Back in May, Parton had been forced to cancel an upcoming Las Vegas residency and took to Instagram to explain – in full make-up and with her hair coiffed to perfection.'The good news is, I'm responding really well to meds and treatments, and I’m improving every day,' she said.But it wasn't the full story.'When she made her recent video telling fans she was receiving treatment but trying to reassure them she was OK, she looked just like the usual Dolly everyone loved,' a source said.'And, underneath one of her famous wigs and after hours preparing her in makeup, she did indeed look camera-ready.' But Parton had all but retreated behind the gates of her sprawling Tennessee compound, allowing the details of her worsening sickness only to be known by an exceptionally tight circle 'She tried to reassure her legions of fans that she wasn't critically ill. But she knew her time was almost up,' an insider said'It was tough for Dolly not to play the sick card when she knew she didn't have long to go. But she was an actress as well as a singer, and she pulled it off incredibly, fooling almost everyone. She didn't want her fans to worry. She wanted them to see the Dolly they've loved for decades.'Right to the very end, she remained determined to protect that polished image.'Dolly occasionally popped up on social media and looked OK as she downplayed her illness, but she was not OK,' another source said.'She relied heavily on filters, makeup and lighting to look good. It was a top priority for her.'But as her health declined rapidly, she withdrew further into herself.'She really didn't leave her home in Tennessee for the past year. She stayed inside,' an insider said.'The house is massive, and there are vast grounds, so she didn't need to leave. Six months ago, I was told that she was not taking on any new projects, that she had to focus on her health, and was not able to travel or have visitors. But no one would say what she had. There were whispers it was cancer, but no one would confirm it.'Publicly, Parton had attributed various recent missed appearances to a handful of manageable ailments, including digestive problems and kidney stones.'We knew it was much more serious than that,' a source said. 'But it was "shhhh, don't ask" from her circle.'In her final weeks, it is understood that Parton was largely confined to her bed.'Her last few days were spent in bed. She was not doing well,' a source said. 'She had lost all her hair, which she didn't have much of anyway as she relied on wigs most of her life. And she was very thin. She was skinny.'It is said that family were by her side.The warning signs had been mounting in recent the months. Before the Caesars Palace residency cancellation in May, Parton had missed a concert celebrating her 80th birthday at Nashville's Grand Ole Opry music venue.A scheduled appearance at Dollywood, her Tennessee amusement park, was also pulled.On June 24, she made her final public appearance, surprising fans for a ribbon-cutting at the newly opened Dolly’s Tennessean Travel Stop. The Cornersville truck stop features a restaurant and sells Parton-themed merch and cups of 'Ambition Coffee', inspired by her iconic '9 to 5' song. 'She really didn't leave her home in Tennessee for the past year. She stayed inside,' an insider claimed (pictured with husband Carl) In May, Parton cancelled her anticipated Las Vegas residency at Caesars Palace'She really tried to be brave [at the truck stop opening], but she was too sick to do anything,' the source said. 'She turned down invites left and right.'While at home, Parton remained focused on DOLLY: A True Original Musical, an autobiographical Broadway show based on her remarkable life and still due to open on what would have been her 81st birthday (January 19, 2027).'She was working on DOLLY: A True Original Musical in New York, but could not travel to check on it,' an insider said. 'She really cared about the project and did not want to jeopardize it.'Parton hailed from one of country music's most famously close-knit families, growing up with 11 siblings in rural and poor Tennessee. Among them was younger sister Stella Parton, now 77, who also forged a career as a country singer.Her loved ones remained fiercely protective.'They never spoke negatively. They didn't talk much about her health issues,' concert promoter Arny Granat, who worked with Parton for years, told the Daily Mail.And as Parton's cancer worsened, the singer is said to have found comfort in those closest to her.'Her sister was always there for her,' another insider said. 'She is very sweet and nurturing. She was by her side all the time.'News of Parton's death has also left her goddaughter, popstar Miley Cyrus, devastated.'Miley is, as you'd expect, shell-shocked by the news,' a source told the Daily Mail. 'It is as deep a grief as you'd imagine, as Miley has always seen Dolly as the strongest woman. The fact she is gone doesn't seem real.'The immediate family was privy to her actual health struggles and the cancer, so this wasn't out of the realm of possibility, but everyone thought she'd battle through it.' The news has also left her goddaughter Miley Cyrus devastated. Above, Cyrus and Parton in 2019'Miley is, as you'd expect, shell-shocked by the news,' a source told the Daily Mail. 'It is as deep a grief as you'd imagine, as Miley has always seen Dolly as the strongest woman. The fact she is gone doesn't seem real' Parton, who never had children, shared a particularly close relationship with Cyrus, appearing on her Hannah Montana TV show and later singing alongside her for various special musical performances.Now, attention will inevitably turn to the extraordinary fortune and business empire Parton leaves behind.Her net worth has regularly been estimated at between $450 million and $650 million, built through music royalties, songwriting, film and television, books, investments and her stake in the Dollywood empire.Details of her will and estate plan have not been made public.She is survived by six of her siblings, as well as a huge charitable legacy led by the Dollywood Foundation and her Imagination Library.For family and fans alike it will surely be some comfort that, in her final months, the woman who spent a lifetime making the world smile was determined not to let the world see her suffer.'She made it seem like she would get better,' a source said. 'But that was Dolly. She really didn't want to share bad news. She was always up and up.'