Mary Jo Eustace, McDermott's ex-wife, has made explosive claims that the star begged her to take him back.
Eustace revealed in an interview with Daily Mail that 11 years after their divorce finalized, the 50-year-old actor continues to diminish his responsibilities to her and his teenage son, Jack.
The Canadian TV star says the most painful part of the ordeal has been watching her 19-year-old son suffer.
'When my son went to university, he didn't get any financial support from his father,' she claims. 'The one thing that his dad was going to do for him was pay his rent and he bounced his rent.'
'It jepardizes his roommates and the apartment. One of the other dads had to cover the rent, so that really humiliated my son. I don't even know if it's paid back yet,' Mary Jo reveals.
Mary Jo also revealed Dean's shocking confession to her while they were taking their son to a Blue Jays baseball game in their native Toronto.
'A year and a half ago, Dean confessed to me that he had made a mistake and he wondered what his life would be like if he had he stayed with me. He said, 'Do I love Tori? Yeah. But I've thrown my life away.''
'We were on the street where we used to live. He fell to his knees crying, saying, 'I can't believe I gave this up.''
Mary Jo finishes by asserting, 'That is 150 per cent true. It was the most bizarre conversation ever.'
Tori Spelling and McDermott have been married for 11 years and share five children together.