Michelle Rounds, Rosie O'Donnell Fiancee, Diagnosed with Rare Tumor Ailment >>Hollywood

Rosie O'Donnell has been forced to delay her wedding to Michelle Rounds, for a terribly sad reason:

Rounds has been diagnosed with aggressive fibromatoses, a rare onset of desmoid tumors that first cropped up on Mother's Day when she awoke with "pain that [wouldn't] let up," according to Rosie's new blog entry.

It took awhile for doctors to determine her loved one's ailment, O'Donnell added, writing of how the couple felt at the time:

"We wander thru the maze of medical mystery confused – scared . . .undiagnosed – again and again, her pain grew worse. It seemed impossible no one knew what was wrong."

Finally, the proper diagnosis was made - there are only 900 new cases of the disease each year in the U.S. - and Rounds underwent surgery in June. Rosie says she's "getting stronger every day."

The couple, who got engaged in December, will now get married next summer. In lieu of gifts, they ask for donations to be made to the Desmoid Tumor Research Foundation.