A former spokesman for the leader of Catholics in England and Wales is suing over a newspaper story which accuses him of hypocrisy over abortion.
The Daily Mail will argue at the High Court that its story was true
Austen Ivereigh, 41, says he lost his position as head of public affairs for Cardinal Cormac Murphy-O'Connor because of the Daily Mail article in June 2006.
His lawyers told the High Court it suggested he "manoeuvred" a girlfriend into aborting, ruining his reputation.
Associated Newspapers, publishers of the Daily Mail, deny libel.
Ronald Thwaites, Mr Ivereigh's QC, told the court the story had "falsely alleged that he was a hypocrite for not practising what he preached in relation to the issue of abortion".
The article suggested Mr Ivereigh "manoeuvred" a student girlfriend into having an abortion 19 years ago after discovering she was pregnant, the court heard.
The Daily Mail had presented Mr Ivereigh - a practicing Roman Catholic - as a "man without honour" who was "unfit to work for the cardinal or for the Church", Mr Thwaites said.
"For this man, few things could be more serious or devastating than that," he added.
Mr Ivereigh "was and is" opposed to abortion, the court was told, a view that was strengthened when his girlfriend terminated her pregnancy against his wishes in 1989 while he was at a graduate college at Oxford.
Mr Thwaites argued that the story in the Daily Mail "was not truthfully told" and that it had been "distorted out of all recognition and combined with some recent events which provided the journalist with a peg on which to hang this sad old story".
The article featured details of another of Mr Ivereigh's relationships, this time with a divorcee - known as Madame X to protect her identity - who had two children and who discovered she was pregnant early in 2006, the court was told.
Mr Ivereigh proposed marriage, but when "problems arose" he "felt that he could no longer commit to marrying her at that time", the court heard.
Although he "made it clear that he would help and support her and the twins that were expected", Madame X seemed to have "made the decision herself that she would have an abortion and refused to have any further contact with the claimant", Mr Thwaites said.
However, Madame X suffered a miscarriage and lost both twins, although Mr Ivereigh did not discover this until "many weeks later" in May 2006, he added.
Giving evidence from the witness box, Mr Ivereigh said his job with the cardinal earned him £46,000 a year and losing it had cost him £20,000.
When contacted by the Daily Mail the day before the story was due to be published, he told the journalist they had got the facts wrong, he said.
"When I saw the article, I was just horrified, astonished. My blood froze. I simply could not believe that they could run this story because these were lies."
He resigned from his job in July 2006.
During cross-examination by Mark Warby QC, Mr Ivereigh agreed he had regular sex with Madame X outside marriage, something which was seen as a sin by the Catholic Church.
"This is one area of Church teaching that I have always struggled with and failed to live out. It doesn't mean I don't believe it," he said.
The case continues.