Madonna concert
Madonna performs during a concert in Herning in November 2015.REUTERS/Claus Fisker/Scanpix

Cross Madonna at your peril seems to be the lesson learned by one unfortunate personal trainer, who had her dirty laundry aired in the most public way possible – in front of a crowd of 20,000 of the singer's most diehard fans. The 57-year-old singer took a break on stage in the Philippines on Thursday night to share a story with the sell-out crowd about an unidentified ex-employee.

"Once I had a Filipino trainer — this beautiful, beautiful girl," she said. "She was gorgeous and very talented as a trainer. But she f***ed my boyfriend, so I fired her."

However, no one can stay anonymous forever when fame is involved, and sleuths quickly zeroed in on Nicole Winhoffer, a trainer who worked for Madonna for five years before they parted ways in 2014.

Winhoffer describes herself on her own website as "born in NYC to a Filipino mother and German father". She also took on the role of creative director for her former boss' Hard Candy Fitness chain of gyms.

Internet gossip site Page Six says that an anonymous source confirmed Winhoffer was the guilty party, adding that "Nicole has been teaching her own method in NYC and acts as if she left Madonna on her own to be an entrepreneur".

Madonna dated two men while she and Winhoffer worked together – Timor Steffens and Brahim Zaibat, both of whom were backing dancers. Madonna split from Steffens, 28, during a holiday to Europe in 2014.

"In this case, it was not a happy ending," said Madonna while on stage. "I know I sound like I'm cynical and I don't believe in romance and that I think everybody is backstabbing."

If the singer can be relied on for one thing, it's controversy on tour. On Tuesday, Singapore's Roman Catholic archbishop told fans not to attend her concerts because she "denigrates and insults religions".

Her current tour, named Rebel Heart, does seem calibrated to upset Christians; at one point in the show dancers dressed as scantily-clad nuns perform on stripper poles shaped like crucifixes.