Gold-digging Gretchen Rossi was an on-camera Florence Nightingale to her dying millionaire fiancé — but the Real Housewives of Orange County hottie had a secret boyfriend all along, according to Jay Photoglou, the man who claims to have been her undercover lover.

“I was Gretchen’s REAL boyfriend,” Photoglou told The ENQUIRER. “She spent her days at the hospital with her dying fiancé, but her nights with me.”

On the popular reality show, 31-year-old Gretchen became engaged to multimillionaire Jeff Beitzel – and several episodes focused on her devotion to the leukemia victim, who died last Sept. 13.

But Jay, 39, says Gretchen was playing for the cameras — and that he recently called off their relationship.

Jay says he and Gretchen began dating in January 2008, and “for the next year we spent most nights together.

“She told me she used to date Jeff, but they were no longer intimate. He was diagnosed in December 2007 and asked her to nurse him back to health. Gretchen’s only job was to take care of him.”

Gretchen told The ENQUIRER: “Jay and I had a short-lived relationship before Jeff and I started dating.” But she called his cheating accusations “ridiculous” and added they were “disrespectful to me and the memories of Jeff.”

You won’t believe who Jay says Gretchen has her sights on now! Hint: He used to be on Housewives! Pick up the new issue of The ENQUIRER to find out and to see the steamy pic of Jay and Gretchen!