Cliff Richard has told a British High Court judge he felt "forever tainted" following BBC coverage of a police raid on his home.
The 77-year-old singer has taken legal action over BBC coverage of the search, which was staged after a sex assault allegation.
BBC bosses dispute his claims.
Mr Justice Mann began overseeing a trial at the High Court in London on Thursday and Sir Cliff started giving evidence today.
He has made a written witness statement and answered lawyers' questions in court.
Entering the witness box, the singer gave his name and swore an oath on the bible.
He told his barrister, Justin Rushbrooke QC, that he prefers to be addressed as Sir Cliff rather than "Mr".
The singer told of the "impact" the broadcast had on him.
"It was shocking and upsetting," he said in his witness statement.
"My health suffered, both mentally and physically."
He added: "At one point ... I actually thought I was going to have a heart attack or stroke."
Sir Cliff said he was conscious that people around the world might think he was a "serious criminal".
"I felt as though everything I had worked for during my life - trying to live as honestly and honourably as I could - was being torn apart," he said.
"I felt forever tainted. I still do."
A barrister leading Sir Cliff's legal team has told Mr Justice Mann that BBC coverage of the search at the singer's apartment in Sunningdale, Berkshire, England, in August 2014 was a "very serious invasion" of privacy.
Justin Rushbrooke QC said the singer should get compensation at the "very top end of the scale".
The BBC says its coverage of the police raid was accurate and in good faith.
Lawyers representing BBC bosses told Mr Justice Mann that the raid was a "matter of legitimate public interest".
They said BBC reporting contributed to public debate.
The trial is due to last 10 days.
Lawyers have told Mr Justice Mann how in late 2013, a man made an allegation to police saying he had been sexually assaulted by Sir Cliff during an event featuring evangelist Billy Graham at Sheffield United's Bramall Lane football stadium, when a child in 1985.
Metropolitan Police officers passed the allegation to South Yorkshire Police in July 2014.
Sir Cliff denied the allegation and in June 2016 prosecutors announced that he would face no charges.
A BBC spokesman has said the broadcaster had reported Sir Cliff's "full denial of the allegations at every stage".
Jason Beer QC, representing South Yorkshire Police, told the court the force issued a "fulsome and unequivocal apology" to Sir Cliff and paid him £400,000 damages in May last year.
The force is asking Mr Justice Mann to rule the BBC should contribute to the damages it paid to Sir Cliff.
The barrister said the force accepted its own "unlawful conduct" but claimed the BBC was "more responsible" for the damage to Sir Cliff.
He said by confirming Sir Cliff's identity to a BBC journalist and by discussing the search warrant, the force acted unlawfully.
But he said it was the BBC's broadcasts which were the "primary cause" of the breach of his privacy.
He added that it was the decision to name Sir Cliff, which the force had made clear it would not do, which resulted in the singer suffering "damage".
Mr Beer told the court that Sir Cliff said his feelings had been "hurt repeatedly" by the behaviour of the BBC.
He added that the singer felt a BBC statement in May last year was "designed to take the sheen off" the settlement and to "undermine the police apology" to him.
Sir Cliff told Mr Justice Mann about seeing footage of the police search on his home for the first time.
The singer's voice cracked as he recalled seeing a news item while at a hotel in Portugal after returning from a winery.
He said the memory was "engraved" and he witnessed footage from cameras which could see "right into" his apartment and had recorded officers searching through his belongings.
He added: "It wasn't a very pleasant feeling and by that time I had heard of the allegation and seeing it made me feel even worse."
Sir Cliff said he did not view any clips of the BBC's broadcasts as they were played to the court on Thursday.
When asked how he felt during the police investigation, Sir Cliff replied: "I have found it very disturbing because it is obvious that for moments, if not days, I was not seen as a human being.
"Everything I had ever lived for seemed to have come to nothing."
During cross-examination by BBC lawyers, Sir Cliff told the court he has spent £3.4m to date on the case.
He said it was "really painful" for him to read a statement from the Corporation criticising him for spending too much money on lawyers.
Sir Cliff broke down as he told the court his name had been "smeared" all over the world by the BBC's actions.
The singer choked up as he listed a number of countries - including Holland, Portugal, Hong Kong and Singapore - where he claims his reputation was damaged.
He said: "Everywhere I have ever been, I felt my name was smeared. The police didn't do that, the BBC did."
He clasped his hands to his face before adding that the journalists involved "felt they were above the law" and "above the Leveson report".