Duncan will go for a pre-nup next time.
But he revealed that if he ever marries again, he will insist on a pre-nuptial money agreement.
The businessman also admitted that his split from second wife Joanne, 47, drove him close to suicide and financial ruin when his fortune shrank from PS430million to PS85million.
Duncan, 64, told an audience at the Cheltenham Literature Festival: "I would marry again - but only with a pre-nup. It's not the money, my children lost everything they were due to inherit.
"They had been going to my house in France for 10 years. They lost that and the place in London - everything they were going to inherit. And I almost lost the company.
"My wife spent PS450,000 on accountants trying to find money that was not there. Now I don't think I'm worth anything much.
"I have a friend whose girlfriend says she will never sign a pre-nup. I told him never to marry her. He's got three children from his wife who died and he has to think of them."
Duncan admitted he was downing three bottles of wine a night before his divorce was finalised early this year.
Twice he thought of killing himself and tweeted "suicide is the considered option".
Duncan added: "It was something I was considering seriously but my kids came around and spent more time with me, so something good came out of it."
He says he is enjoying life again with his family and spends a lot of time at his Lake District home, where he waterskis and wakeboards on Windermere with his son Tom, 12.