A former MP broke down in court as he recalled being named a child murderer and paedophile by a man later charged with lying over the claims.
Harvey Proctor was giving evidence as a witness in the trial of Carl Beech, 51, who has been accused of lying to police about an alleged VIP paedophile ring.
Mr Beech denies 12 counts of perverting the course of justice and one of fraud.
He had claimed Mr Proctor was directly involved in two murders and multiple counts of abuse in the 1970s and 1980s.
Giving evidence at Newcastle Crown Court, Mr Proctor was asked by prosecutor Tony Badenoch QC how he felt about being accused of "the murder of children and of sadistic sexual offending".
The former Conservative MP replied: "The allegations are wrong, malicious, false, horrendous."
Mr Beech, from Gloucester, was known by the name "Nick" when his claims were first reported in the media.
He is on trial accused of lying about being sexually abused by a group of well-known figures from politics, the media and intelligence. He also told police he had witnessed three boys being murdered.
His claims led to the Metropolitan Police's Operation Midland, which cost £2m and ended without any charges.
As well as Mr Proctor, among the people he accused of being in a paedophile ring were former prime minister Sir Edward Heath and former Home Secretary Lord Brittan.
Mr Proctor told the court he had a hostile relationship with Sir Edward - describing them as "the antithesis of friends" and neither was welcome at the other's home.
Jurors had previously heard how Mr Beech claimed he was let into a Conservative gentlemen's club - the Carlton Club - by Mr Proctor, and was then abused.
Mr Proctor said he had "never met Nick" and the allegations were "an absurd fantasy".
He told jurors: "He is wrong. He is bearing false witness. There was no Westminster VIP paedophile ring."
Jurors heard that Mr Proctor's home in Leicestershire was raided by police on 4 March 2015. He was living and working at the Belvoir Castle estate at the time, having left Parliament in 1987.
Detectives did not disclose the details of the allegations against him during the 15-hour search, Mr Proctor said.
He became tearful when he described waking the next morning to discover the BBC reporting news about his home being searched in relation to claims of abuse and murder.
"I looked up at the television to see my face looking back at me", he said, adding he then called the Radio 4 Today programme and said publicly - during a radio interview - that he had been plunged into a "horrendous irrational nightmare" and "was not guilty of any of the allegations".
Police statement 'extraordinary'
Mr Proctor said intense media interest following the police raid led to him losing his job. He then decided he "wasn't safe" in the UK and moved to Spain, the court heard.
He told jurors that "the Metropolitan Police believed the allegations against me were credible and true".
The witness said a senior Met officer - Det Supt Kenny MacDonald - had given a press conference early in the inquiry and described the claims in such terms.
"I thought it was an extraordinary statement to be made by any police officer at the start of a police investigation", he said, adding that he had not realised the detective was talking about him when he first saw it.
He returned to the UK to be interviewed by police on 18 June 2015. In the days beforehand, his solicitors showed him a document setting out the claims that detectives wanted to ask about: three allegations of murder and several allegations of sexual abuse of children.
Jurors have previously been shown a video in which the defendant told detectives he saw Mr Proctor strangle and stab a boy to death during a sadistic sexual abuse session.
Mr Beech also said Mr Proctor had been involved in the murder of another unknown child.
"These were horrendous, horrible, heinous allegations," Mr Proctor said. "These are the worst things that one person can say against another. It was all untrue."
He said he was "relieved" to finally know what he was accused of so that he could "fight back against these false allegations".
The trial will continue on Friday.