Rosie O'Donnell and Michelle Rounds. Picture: Bang Showbiz

Rosie O'Donnell's ex-wife Michelle Rounds, has died in an apparent suicide, TMZ reports.

Michelle, 46, who tied the knot with Rosie in 2012 before splitting up two years later, was found dead at her home on Monday and Rosie spoke of her sadness at the tragedy.

Speaking about Michelle - with whom she has daughter Dakota, four - Rosie, 55, told TMZ: "I am saddened to hear about this terrible tragedy. Mental illness is a very serious issue affecting many families. My thoughts and prayers go out to Michelle's family, her wife and their child."

Michelle's mother said in a statement: "If anyone would like to give to the National Suicide Prevention it would also be greatly appreciated. There are so many out there in this world that have demons that they think suicide is the only way out."

Rosie filed for divorce from Michelle in 2015 and their union was dissolved last year after they spent 15 months working out a settlement. 

And last year, Rosie confirmed she had sole custody of Dakota, in an 'Ask Ro' Q&A on her website.

When a fan asked Rosie if she shared custody with ex-wife Michelle, she replied "I do not."

Another fan asked if Michelle was out of the child's life, and she replied "Yup".

Rosie and Michelle had a secret wedding in 2012, after they moved up the date following Michelle's diagnosis of desmoid tumours; noncancerous growths that occur in the connective tissue. 

Rosie wrote on her blog at the time: "We married in private before [Michelle's] surgery, just the [two] of us. When we r both well enough will have the wedding of r dreams surrounded by those we cherish.

"Thankful for the love and support so many have given us during these trying times. Including all of u stranger-friends connected thru invisible strands of wi fi (sic)."