Speaking on the Howard Stern Show, the Hole rocker said she had a "vision of marrying Gavin Rossdale" during their eight-month relationship in the mid nineties.
"Everyone gave me so much s--t because Gavin sounded a lot like Kurt [Cobain]," she said. "But man, he was such an Adonis in his day!"
"He got good in bed … something happened. Maybe Gwen taught him, for all I know."
Stern pushed her on her slip up, "You were [having sex with] him while he was with Gwen Stefani?"
"Yes," Courtney replied. "She does know."
"You mean he was having sex with you while he was with her?"
"Everyone … yeah … and a few other people," Courtney replied. "We didn't have a lot of pressure on each other, but we did like each other quite a bit."
Gwen and Gavin, who married in 2002 and have two sons, are yet to comment on Courtney's claims.