Hidden under the name Soraya, the author recounted that the dictator first saw the girl when he visited their high school in April 2004. She was then 15 years old. A day after the school event, Gaddafi's emissaries visited Soraya's home and informed her mother that Soraya was coming with them for an hour.
It was an hour of hell with Mr Gaddafi raping the teenager.
"I remained motionless, so he leaped to his feet and with a force that took me by surprise he grabbed my arm, threw me on the bed, and flung himself on top of me," wrote Ms Cojean, quoting Soraya.
Soraya was one of Mr Gaddafi's sex slave whom he even brought in public functions disguised as security staff. According to Soraya, the dictator demanded sex from the women daily and even share them with his favourite minister and military commanders.
Besides teen girls, the dictator also raped male guards and boys and even pursued celebrities and wives of foreign diplomats.
Soraya was allowed to go home in 2009, but her family is ashamed of her because she had sex outside marriage.
The book sold over 100,000 copies since it was published in French in 2012. The English translation will be released in September.
Soraya said she only felt free in October 2011 when Mr Gaddafi was captured and killed while trying to escape the home town of Sirte. In a fitting end to the abusive ruler, reports said that before he was shot, the dictator was sodomised by his captors.