In an interview that took place in a New York restaurant and was published Friday in Britain's The Sun, Sollecito criticized prosecutors in Italy for seeking a third trial.
"The prosecution has a theory without real evidence or facts. It is extremely painful. It seems so personal, like they are determined to draw me back into this nightmare," he said. "I survived the flames of hell once and now they are pulling me back into them. It feels like a war. I was 23 and had just met a great girl."
Sollecito and Knox met while she was on a year abroad in Perugia, Italy. They were convicted of killing Kercher, a British student who was Knox's roommate, student, and then acquitted by an appeals court.
Rudy Guede, a native of the Ivory Coast who grew up in Perugia, was convicted at a separate trial and remains in prison. Prosecutors say Sollecito and Knox committed the crime with Guede during a drug-fueled sex game.
The Italian Supreme Court recently ruled prosecutors could hold another trial. Knox, a former student at the University of Washington, has returned to the Seattle area and it is not clear if she can be forced to go back to Italy.
Sollecito said his relationship with Knox was "like being hit by a thunderbolt." He said they do not have a romantic or sexual relationship now but remain friends and met recently in New York.
"We have been through such a huge thing together that it is natural we would remain friends and support each other," he said.
Sollecito's father has criticized prosecutorial comments on the case. Giovanni Galati, the prosecutor in Perugia, said this week that the high court decision "substantially demolishes" the appeals court ruling.
Francesco Sollecito told the Italian newspaper La Nazione Umbria that Galati's statement was "unusual and improper," The Local.it reported.