"It's with great sadness that Tom & I agreed to divorce," she wrote. "We care for each other very much, hope you respect our privacy during this sad time!"
De Lesseps, 52, and D’Agostino, 50, let reality show viewers watch their intimate New Year's Eve nuptials in Palm Beach, Florida, earlier this year.
De Lesseps even confronted her estranged husband about a cheating rumor last season. She eventually decided to go ahead with the wedding.
This was the first marriage for D’Agostino and the second marriage for De Lesseps. She was previously married to Count Alexandre DeLesseps from 1993 to 2009 and has two adult children, Noel and Victoria.