Goncalo Amaral said he had been the victim of “an attack against freedom of expression”.
He added: “I am a free man and like any other citizen in this country I have the right to express my opinions.”
Mr Amaral, 55, has been told to hand over £357,000 after accusing Kate McCann, 47, and her husband Gerry, 46, of covering up their missing daughter’s death in his best-selling book.
The ex-officer, who headed the initial investigation into Madeleine’s 2007 disappearance, is appealing the ruling by a Portuguese judge.
He claimed he had been “tried over an offence of opinion”.
Mr Amaral said the damages would bankrupt him.
He added: “My life is gone. I’m only alive due to my heart.”
He told Portuguese weekly magazine Nova Gente everything in his book was contained in official police files.
Yet the judge’s ruling meant the McCanns were “worth more than any Portuguese citizen dead or alive” and “above any god or divinity” in that they could not be “criticised, ridiculed and satirised”.
He said: “Look at the discussions about the terrorist attacks against French newspaper Charlie Hebdo.
“With my book I did not defame, nor did I have the intention to defame anyone, but merely to report what happened during the first five months of the investigation thus replying to the attacks against my good name and my professional dignity.”
Mr Amaral plans to countersue the McCanns. He said: “It is a fact that they lost their daughter but that doesn’t give them the right to sue anyone or to be compensated.”
The McCanns, who sought £1million damages, told the libel hearing they were “devastated” by his allegations.
