The 23-year-old bartender who

allegedly overdosed in the Central Park South apartment

of real-estate mogul Ian Reisner collapsed from a cocktail of molly and cocaine while having sex in the shower during a wild night of party­ing, law-enforcement sources said Thursday.

Sean Verdi, of Bay Ridge, Brooklyn, started convulsing Wednesday morning in one of the $20 million home’s six bathrooms during one of the mogul’s parties, sources said.

Reisner, 45, owner of Out NYC, the city’s first gay-centric hotel, had been surrounding himself with an entourage of attractive young men and throwing all-night ragers at his luxe, French art-deco duplex, one pal said.

Verdi’s cause of death is still under investigation, said a spokesperson for the city Medical Examiner’s Office.