Nadja Benaissa, a member of German girl band No Angels, admitted in court she had unprotected sex despite knowing she was HIV-positive.
The 28-year-old is charged with grievous bodily harm for allegedly infecting her partner with the virus in 2004 and also faces charges of attempted bodily harm for having unprotected sex with two other men.
"I am sorry from my heart," she said in a statement read by her lawyer to the Darmstadt court. "No way did I want my partner to be infected."
The man who claims Benaissa infected him says they had a three-month relationship in 2004, and that he got tested after Benaissa's aunt asked him in 2007 whether he was aware that the singer was HIV-positive.
Prosecutors say Benaissa had known she was HIV-positive since 1999.
Benaissa was arrested in April 2009 and kept in custody for 10 days.
Benaissa joined No Angels in 2000 through the TV casting show Popstars. The group sold more than five million albums before breaking up in 2003 but reformed in 2007 to represent Germany in the 2008 Eurovision song contest.