A singer from German girl band No Angels has admitted to having unprotected sex with several partners without warning them she was HIV-positive.
Nadja Benaissa, 28, was speaking at the opening of her trial in the German city of Darmstadt.
"I am so sorry," Ms Benaissa told the court. However, she denied deliberately infecting anyone.
She faces a charge of grievous bodily harm for allegedly infecting one man.
She has also been charged with attempted bodily harm for allegedly having sex with two other men who were not infected.
The charges carry a prison sentence ranging from six months to 10 years.
"When I was arrested I realised that the way that I had dealt with the illness had been wrong... I made a big mistake," said Ms Benaissa, in a statement read to the court by her lawyer.
"No way did I want my partner to be infected."
She claimed she had been told by doctors that the risk of passing on the virus was "practically zero".
She also feared that admitting her infection "would probably have meant the end for No Angels", her lawyer, Oliver Wallasch, told the court.
Held in custody
The man who was infected with HIV said he learned that Ms Benaissa was HIV positive from her aunt, and went to his doctor for a blood test straight away.
The unnamed man told the singer in court: "You have created a lot of suffering in the world."
Ms Benaissa was arrested in Frankfurt last year, shortly before she was due to perform a solo concert, and spent 10 days in custody.
No Angels were formed in 2000 on the international TV show Popstars, before recording a series of hits and emerging as Germany's most successful girl band.
They re-formed in 2007 and competed in the 2008 Eurovision Song Contest, finishing 23rd.
Ms Benaissa's trial is expected to end later this month.
Risk of stigma
Aids campaigners have been critical of the authorities' handling of Ms Benaissa's case, and warned against a rush to criminalise the transmission of HIV, the BBC's Tristana Moore reports from Berlin.
Edwin Bernard, a writer and advocate specialising in HIV prosecutions, believes that prosecutions and laws on HIV transmission may do more harm than good in terms of reducing the spread of infections.
He told BBC World Service that studies in the US had found that they have had no real impact on new infections.
When the 24 US states which have disclosure laws were compared with those that do not, there was no impact on the rate of transmission or the level of unprotected sex people engage in, he said.
"By singling out HIV, it really promotes fear and stigma," Mr Bernard added.
"Many of these cases, and in particular the media reporting of these cases, perpetuate an awful lot of myths about how HIV is transmitted, as well as things like the life expectancy, which is pretty close to normal now in the developed world."
The campaigner noted that prosecutions were relatively rare compared with the number of HIV transmissions that happen each year.
He estimated that there had been at least 600 prosecutions in more than 40 countries with prison sentences handed down in most cases, ranging from a few months to life.
Very few people, he said, had been prosecuted for intentionally transmitting HIV sexually.