Tommy Sheridan told jurors that his life and reputation were on the line in his £200,000 defamation action against the News of the World.
The former Scottish Socialist Party leader repeatedly said he would be an "idiot" if he had cheated on his wife, visited swingers sex clubs and participated in orgies.
Sheridan appeared close to tears on several occasions during the 85-minute speech in which he branded the paper "liars and hypocrites".
The Glasgow MSP also told a packed Court of Session in Edinburgh that the life of his unborn baby had been put at risk by the newspaper's claims, in November 2004, that he had a four-year affair with former prostitute Fiona McGuire.
He told the jury that he could not bring himself to hate or despise her as she was also a victim in the case, which has now run for 21 days.
At the start of his speech, Sheridan, who is representing himself, told the jury he was not a legal practitioner, but rather that he was a socialist politician with a "reputation for honesty, integrity and hard work".
Sheridan said he was going head-tohead with Michael Jones QC, for the newspaper, who he described as one of the best advocates in Scotland.
But he added: "To Mr Jones, this is just another job. To me, it's my life and reputation that is on the line."
Recapping on the sensational evidence, Sheridan said: "From three in a bed to four in a bed. From four in a bed to five in a bed. From five in a bed to sex clubs. From sex clubs to champagne.
From champagne to cocaine. From cocaine to orgies in a hotel slap bang in the middle of Glasgow.
"The allegations in the course of this case have been as numerous as grains of sand in the Sahara Desert. But evidence — real tangible, substantial evidence — has been conspicuous by its absence."
The MSP rubbished claims that he had sexual relationships with McGuire, former SSP candidate Katrine Trolle and, while he was married, with News of the World journalist Anvar Khan.
He also dismissed the "dodgy minute" of the party's emergency executive committee meeting of 9 November 2004, at which some members, including three MSPs, said he had admitted attending a swingers club.
Sheridan told the jury: "The case against me on behalf of the News of the World has not produced a single smoking gun, but it has featured plenty of smoke and mirrors."
Sheridan even offered to strip in court to prove his wife's evidence that he has excessive body hair, a distinguishing feature not mentioned by any of the women who said they had slept with him. The public gallery erupted with laughter as the MSP recalled his wife's testimony that he was "like a hairy ape".
During his speech the MSP referred to McGuire as the main witness in the case against him.
The court previously heard the former escort girl was paid £20,000 for her story, published on 14 November 2004, that she had a four-year affair with Sheridan which included group sex.
Sheridan told the jury the News of the World story featuring Fiona McGuire had been printed when his wife, Gail, was three months pregnant with the couple's first child.
Sheridan claimed the tabloid was only concerned about sales and not people's lives.
For the News of The World, Jones, opening his speech, said: "What lies behind this is a truly monstrous ego — Mr Sheridan's ego."