Kate McCann has told for the first time her own account of when she discovered that her daughter, Madeleine, had been snatched away from her.

In her 384-page self-penned memoir, serialised in The Sunday Times and to be published this Thursday, on what would have been Madeleine’s eighth birthday, Kate describes the maelstrom of emotions that overcame her (‘nausea, terror, disbelief, fear, icy fear, dear God, no’) as she was confronted with every parent’s ultimate nightmare.

Former GP Kate, now 43, reveals how losing their daughter drove her to the brink of suicide and came close to breaking up her marriage to cardiologist Gerry McCann.

Madeleine was snatched from the McCann’s holiday apartment in Praia de Luz, Portugal, as her parents dined with friends on the final night of a spring break in May 2007.

Madeleine and her brother and sister, twins Sean and Amelie, now aged six, had been left alone in the apartment while Kate and Gerry McCann dined close by, checking on the children every half hour.

On one of those checks Kate McCann discovered the bedroom window open, the shutter raised from the outside and her daughter missing. She ran outside screaming, “Madeleine’s gone! Someone’s taken her!” However, during the following days McCann appeared curiously composed.

Her apparently controlled response to Madeleine’s abduction four years ago, turned Kate into a hate figure.

In her new book, Madeleine, Kate says she went into shock. “It’s quite frightening when I see myself in those early days,” she says. “To me I look incredibly fragile and confused and lost.”

Within hours of Madeleine’s kidnapping, internet forums were abuzz with comments from people who did not believe the couple’s story or regarded Kate as a “cold emotionless woman”.

As criticism intensified into hysteria, Kate tells how in private she was breaking down. “I had an overwhelming urge to swim out across the ocean as hard and as fast as I could; to swim and swim and swim until I was so far out and so exhausted I could just allow the water to pull me under and relieve me of this torment.”

Privately, she says, she was – and sometimes still is – “consumed” by overwhelming guilt and anguish.

By day, she would replay hideous images of Madeleine’s broken body “lying cold and mottled on a big, grey stone slab”; or in the hands of some twisted sex fiend.

“The idea of some monster like this, touching my daughter, stroking her, defiling her perfect little body, just killed me over and over again,” she writes.

“It didn’t make any difference that this might not be the explanation for Madeleine’s abduction (and please God it isn’t). The fact that it was a possibility was enough to prevent me from shutting it out.”

An entry from her diary during those early days reads: “Crying in bed again. The thought of Madeleine’s fear and pain tears me apart. The thought of paedophiles makes me want to rip my skin off.”

At night, her torment comes by way of vividly lifelike recurring dreams. Kate has three, and they are broadly the same. Madeleine is still alive, and so tangible her mother can “smell her, feel her snuggling into me, like she always did”.

Then she wakes up, and the daughter she and Gerry strove so hard to conceive after months of IVF treatment is no longer in her arms. It is as if she has been ripped away from her all over again.

Though her 42-year-old husband was able to resume a semblance of normality much sooner than his wife, his outwardly tough exterior is deceptive, she suggests.

One day, watching his daughter’s favourite Dr Who episode with the twins, she found him silently dissolving into tears.

British police later told the couple that the location of the family’s holiday apartment, on the ground-floor corner of a five-storey block accessible from both the front and side, and partly hidden by trees, made it an ideal target for a child abductor.

However, it was only 18 months later, when the Portuguese authorities formally shelved the inquiry and opened the case file, that Kate and Gerry discovered the chilling gamble they had unwittingly taken by holidaying in such a vulnerable location on the Algarve.

Logged in the papers were five reports where British parents had complained that their children had been sexually molested in their beds as they slept and three more where the intruder had been disturbed before he could assault his would-be victims – again, young Britons on holiday.

Not one of these cases had been mentioned to the McCanns, and Kate says there was “a familiar thread”– that none appeared to have been taken seriously, either by the Portuguese police or the tour operators concerned.

The hunt for Madeleine continues and hundreds of questions remain unanswered.

One only hopes the many questions raised in Kate’s book will prick the conscience of the Portuguese authorities and prompt them to review the police investigation.

It is hoped the royalties from it will keep the McCanns’ private investigators in business long enough to turn up a crucial lead.