"Two things about Belle Gibson are hard to believe," began a story in a popular lifestyle magazine. "The first is that she's only 26 years old, and the second is she has terminal brain cancer."

The first of these details has now been disproved. The second is under a cloud after contradictory claims about the Melbourne app developer and health blogger's medical history were exposed.

This time last week, Gibson was a social media starlet and the darling of Apple. The 23-year-old was enjoying international acclaim for her recipe app, The Whole Pantry, and a new book by the same name was weeks away from international release.

Gibson markets herself as a picture of clean living. Vivacious and wholesome, she has been her own best advertisement. And her 200,000-strong online following has hung on every word and image released through her carefully managed social media pages.

But privately last week she was bracing for the backlash that would come after her philanthropic claims were finally tested.

Gibson hoped it would all go away. In her 1500-word response to Fairfax Media's questions about her fundraising activities, she said she was confident her explanation "rectifies any confusion". But her comments, which failed to address many holes in the claims about her charitable donations, only focused the spotlight.

And as quickly as she rose to success, it began to unravel. Gibson, who last year elicited an outpouring of support when she posted online that her cancer had spread to multiple organs, admitted she may have been misdiagnosed. Then her close friends spoke publicly for the first time, saying they feared that she may not be sick at all.

Within days, Consumer Affairs had started asking questions about Gibson's fundraising activities and her publisher, Penguin, was investigating the accuracy of the story it admits never verifying. The US book deal hangs in the balance. Apple refuses to speak her name. Her staff have started abandoning her.

Gibson's fans, and the wider public, also turned. Her home address was published online and she is said to have received death threats. Hundreds of vicious comments directed at The Whole Pantry founder detail her devotees' feelings of "betrayal" and heartbreak. Her journey of cancer survival, which brought hope to many thousands, still has many unanswered questions.

One fan said: "I bought your app. I bought your cookbook. I read about you in Marie Claire. I watched you on various TV shows. I followed you on Instagram. I rooted for you and felt sad for you when you posted about your cancer spreading. And now I am just appalled."

Hundreds have voiced their outrage after holes started to emerge in the "inspirational" life story Gibson used to build her brand. Cancer survivors and their families, charity workers, and TWP customers are further aggravated by her refusal to speak in the face of growing calls to produce evidence of her illness.

The silence from the Gibson camp has been deafening. Of the dozens of former friends, colleagues and schoolmates to speak out this week, just one – an old classmate – has contacted Fairfax Media in Gibson's defence, saying her credibility is "strong". No family has come forward.

Gibson herself has gone to ground and is not responding to calls and emails. Thousands of posts have been deleted from her social media accounts, including details of multiple cancer diagnoses, heart problems and seizures.

Along with other medical specialists, leading neurosurgeon Professor Andrew Kaye doubts Gibson's health claims and has condemned people who profit from baseless health claims.

"There are unfortunately some totally unscrupulous people, and I'm not necessarily referring to [Ms Gibson], who make claims that are just not validated for the treatment of malignant brain cancer," he said. "These people are extremely cruel because they prey on patients who are extremely vulnerable and hoping to find a cure for what is essentially an incurable disease ... they perpetuate the cruellest form of hoax."

Those who were once close to the app developer – and who are acknowledged in her book – say they were sought out by Gibson. Many of them have built their own successful businesses in the health, nutrition, technology and creative industries and say they were flattered. Now, they say they feel they were pawns in her rise to success. "I admired her and loved her," said one. "Now I feel like an idiot."

Gibson's inner circle started raising doubts about her diagnosis last year, and say that after confronting her she failed to provide any evidence of being sick. They point to the overseas holidays between worsening cancer diagnoses and a public profile they say is at odds with the reality of the glamorous life she leads.

Gibson has advocated dumping conventional medicine in favour of natural therapies and traded off her philanthropy for social and environmental causes, having said she gives away "almost all profits".

Despite recently promoting the success of her business she now says it is running at a loss. Her former friends say this has not stopped her living a five-star lifestyle: designer clothes, $2000 handbags, first-class international travel. Gibson rents a luxury beachside apartment in Elwood and drives a BMW 4WD.

In the 3000-word preface to her book, Ms Gibson writes about why her social media success resonated with so many: "Authenticity and integrity. It really is that simple," she said. "Too many people over-edit themselves. I used to be quite self-conscious and sheltered, but now I embrace rawness and honesty."

Do you know more? Email beau.donelly@fairfaxmedia.com.au or nick.toscano@fairfaxmedia.com.au