Show business veterans Bert and Patti Newton struggled with their son's erratic behaviour since he was a child and warned him about it while dating actors Rachael Taylor and Brooke Satchwell.
"With both of them I said: 'Be careful, they are young beautiful girls and they won't put up with being shouted at'," Mrs Newton said in an exclusive interview with A Current Affair aired tonight.
She said her 33-year-old actor son is currently on suicide watch while seeking help at a mental health clinic in Sydney.
The Underbelly star and former X-Factor judge has been embroiled in allegations he attacked former fiancee Rachael Taylor while in Rome.
Three-and-a-half years ago he was charged with assaulting former Neighbours star Brooke Satchwell after a bitter end to their relationship. The charges were later dropped.
When asked tonight if her son had said he wanted to self-harm, Mrs Newton said: "Many times."
"He's the saddest I've ever seen anyone," she said in the ACA interview.
"He's lost the girl of his dreams … that is the toughest thing."
She and husband Bert said their son was now taking medication to curb his outbursts, which began when he was a child.
"Years ago bipolar was mentioned [by doctors] … but he wouldn't take [medication], he would never want his creativity to leave him," Mrs Newton said.
Both parents said the latest drama had "exhausted" their patience.
"Bert and I don't know where to turn or what to do", Mrs Newton said.
Bert Newton added: "Matthew has to get back to being healthy again … There's one lesson to be learned and there's one person to learn it, and if that can be done, hopefully he can be okay," he said.
* Readers seeking support and information about mental health problems can contact Lifeline on 13 11 14 or SANE Helpline on 1800 18 SANE (7263).