The 55-year-old comedian and her ex broke up in 2014, and have a four-year-old daughter together.
Rosie O'Donnell's ex-wife, Michelle Rounds, died unexpectedly in her home on Monday at age 46.
“I am saddened to hear about this terrible tragedy," O'Donnell said in a statement to ET. "Mental illness is a very serious issue affecting many families. My thoughts and prayers go out to Michelle’s family, her wife Krista, and their child.”
Rounds death is being considered an apparent suicide, TMZ reports.
However, a spokesperson for the Orange County (Florida) Sheriff’s Department tells ET, “They are not calling this a suicide at this time," adding, "they are calling it a death investigation. We are waiting for the autopsy to come back.”
The pair broke up in 2014, and share a 4-year-old daughter together, Dakota.
Rounds' obituary shared that her family will hold a private memorial, adding that no public service will take place.
Rounds' mother shared the following statement on her Facebook page, "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."
If you or someone you know needs help, please call the National Suicide Prevention Lifeline at 1-800-273-TALK (8255).