Mary Jo Eustace married actor Dean McDermott on July 24, 1993. She moved to Los Angeles when McDermott went south to develop his acting career.
She gave birth to their son Jack Montgomery McDermott (born October 10, 1998) when she was 41, and were in the process of adopting a baby girl, Lola, when McDermott began his affair with Tori Spelling.
After 13 years of marriage, McDermott and Eustace divorced on February 12, 2006, and he married Spelling three months later.
She later finished the adoption of her daughter Lola Eustace (born April 2005) in July 2005 aged 47 as a single parent.
Although McDermott was awarded joint custody of their son Jack, Eustace moved back to Canada with her children. She returned to Los Angeles in 2008.
Eustace wrote about the break-up of her marriage in the book "Divorce Sucks: What to do when irreconcilable differences, lawyer fees, and your ex's Hollywood wife make you miserable" which was released in October 2009. She also wrote about her personal divorce story in "Palm Springs" (an essay contributed to The Other Woman, a collection of stories from 21 women).