Frankel had announced she and Hoppy, her husband of nearly three years, were separating on December 23 but avoided any mention of divorce at the time.
"It brings me great sadness to say that Jason and I are separating. This was an extremely difficult decision that as a woman and a mother, I have to accept as the best choice for our family," she said in the December statement.
"We have love and respect for one another and will continue to amicably co-parent our daughter who is and will always remain our first priority. This is an immensely painful and heartbreaking time for us."
Frankel and Hoppy met in November 2008 and got engaged 11 months later. They wed in March 2010 when Frankel was seven months pregnant with their two-year-old daughter Bryn.
Bethenny Ever After showed footage of Hoppy and Frankel -- who first appeared on reality TV when she competed on The Apprentice: Martha Stewart in 2005 -- struggling in their marriage, and reports had circulated for months that the couple was on the verge of calling it quits.