Ramona Singer has filed for divorce from her husband Mario, ABC News confirmed.
New York County Clerk's office said there is a divorce case open against Mario Singer that is "so new" there isn't even a date attached.
Singer, a star on the "Real Housewives of New York," has been married for 20+ years, but a source recently told People magazine that Ramona caught Mario with a new girlfriend at the couple's Hamptons home.
"Ramona has been protecting him," her former co-star Jill Zarin told the magazine. "She looked the other way when people told her he was cheating."
Singer has not publicly confirmed the move for divorce. However, Ramona did tweet a message of gratitude to her fans.
"Thank you all for the love & support! For my daughter's sake, I would appreciate everyone respecting our privacy during this difficult time," she wrote.
A rep for the couple had no comment, and neither Ramona nor Mario has commented on the cheating allegation.