Sipping mineral water in a Left Bank hotel in Paris, Kristiyana Valcheva is so well groomed and self-confident, gracefully smoking long, thin, white cigarettes, that it is impossible to imagine the horror she has been through. “You know, that’s often been a problem for me: looking well when in fact I’m feeling awful,” she says coolly. “That can make people jealous.”

Valcheva, 48, is one of a group of Bulgarian nurses who were suddenly released three months ago - following an intervention by Cécilia Sarkozy, wife of the new president of France – after eight years in prison in Libya on trumped-up charges of infecting more than 400 children with the Aids virus. The group were convicted after being tortured to obtain a “confession” and faced execution by firing squad.

As the supposed ringleader, Valcheva was particularly badly treated, so much so that she survived only by building an emotional “shell” around her that stopped her feeling sadness or fear. She still cannot cry, but after her release she went bungee jumping to see if she would feel any emotion. She was relieved to find that yes, she felt afraid, but her elegant appearance is a signal of defiance against her captors. “When I die I will leave instructions in my will that I want to be very well made-up in the coffin,” she says. “I don’t like to be pitied.”

From the start, western governments and human rights campaigners denounced the charges against Valcheva and her colleagues as a travesty of justice, but it was only this July, when a secret diplomatic mission saw Cecilia Sarkozy negotiate with Colonel Muammar Gadaffi in his tent, that Valcheva and the others were released. Escorted by Cecilia Sarkozy to a jet that spirited the nurses away to freedom, Valcheva exclaimed: “We have gone from hell to paradise!”

Three months on Valcheva has published in France an account of her Libyan ordeal, J’ai Gardé la Tête Haute (I Held My Head High), which graphically describes the violence she endured. It is a formidable portrait of a woman who never lost her dignity.

Born to a builder’s family in Sofia, the Bulgarian capital, Valcheva earned so little as a nurse at home that in 1991 she decided to settle abroad; she chose Libya for its sunny weather and good wages. Her husband, a doctor, had also found a job there.

She started working in a haemodialysis unit in Benghazi, a mile away from the children’s hospital where the Aids affair broke in 1998. What she saw of the country’s health system struck her as chaotic and starved of funds, but she knew nothing about conditions at the children’s hospital.

Then, one evening in February 1999, police arrested Valcheva outside her home in Benghazi, blindfolded her and drove her to Tripoli. Four other nurses and a Palestinian doctor were among those also arrested. The Libyans accused her of being a mafia godmother, the head of a gang backed by Israel’s Mossad secret service, which had been paid $10,000 to inject Libyan children with the Aids virus.

“I wasn’t even working at the hospital where the infection was,” she says, in her first interview with a British newspaper.

She was held in a training school for police dogs for just over a year, then in jail. “The looks the guards gave us said we were child-killers. These were uneducated guards who believed in the plot scenario. During the first months they threatened to bring my son from Bulgaria and to torture him. They said they’d do the same thing to my husband.”

The physical torture began a week after her arrest. At first she was stripped naked and whipped on the soles of her feet with a metal cable wrapped in plastic; the soles of her feet became one huge blister.

She was also hung by her wrists with a sheet from a window. A guard she knew only as Muhammad spat in her face. He forced some ash from his cigarette into her mouth; then he put the cigarette close enough to her toe, where the nail begins, to burn her skin.

She can still remember the Arabic word for what followed: “alkhrbaa’a” (electricity). Guards made her lie down on a mattress and attached wires linked to an electric generator to her toes. “The pain generated by this machine paralyses you,” she writes. “If there is a physical feeling corresponding to madness, this is it . . . Not one cell of the body escapes the pain.”

Another guard she called “the Dog” put a tape-recorder by her ear so she could hear her fellow nurses accusing her. Over several hours she was given electric shocks four times. “I twisted and turned like a worm, you could smell burnt flesh. It was impossible to cry or to beg, I had become a block of fear and of instinctive reflexes. To cry, you have to be able to think. I no longer had a brain.”

Her whole body trembling, she heard herself shout: “I’m guilty! I’m the one who brought the Aids!” The torture stopped, but only briefly as her guards demanded more and more details of the non-existent plot.

Valcheva says in a matter-of-fact tone that, as the suspected head of the plot, she suffered more than the other prisoners. She was sexually abused by the Dog and his superior, whom she called “the General”. They made her undress, then the General touched first her nipples then the rest of her body with a resin baton generating electric shocks.

Much later she found out that her husband, Zdravko, had been arrested when he came to Tripoli to search for her. He was released but Valcheva, the other nurses and the Palestinian doctor were condemned to death at a first trial in 2004 and again after a retrial in December 2006.

Their sudden release this summer sparked a controversy: a few days later France signed a missile deal and a memorandum of understanding for a nuclear energy agreement with Libya. The French parliament set up a commission last week to look into what went on. Valcheva shrugs. “I don’t have the details, I don’t know what deal there was. I suppose there was one, but as far as I’m concerned the point is that I’m free,” she says.

Part of the deal was a pledge by Valcheva and the other prisoners not to sue anyone over her detention. She has no regrets over signing; she has already spent eight years in judicial proceedings, to launch new ones would be pointless. “All I’d like is for Libya to understand why not only the children but so many adults as well have been contaminated,” she says.

She is sure about one thing: she does not want to think about her ordeal any longer. “I did the book because I wanted to get all this out of me. Now I intend to forget it all,” she says.

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