Katherine thought Paul was her Prince Charming. Then she found out about his other wife.

Katherine de Bois was happily engaged to Paul Carter with a 3.5 carat sparkler on her ring finger, just 12 weeks after she met him online.

Their engagement party at Melbourne’s State Library in 2014 cost $250,000 and she wore jewels draped across her décolletage and around her wrist.

Paul told her he’d been married before, but his late wife sadly died from bone cancer eight years prior.

Here’s a snippet from the 60 Minutes story about Paul Carter. Post continues after video.

He described to her in detail what his beloved Brooklin’s final graphic moments were like; “she had rotten breath, and hollow sunken eyes,” he told her.

The self-made property mogul showered her with gifts, picked her up in flashy sports cars and told her she was the love of his life.

But everything about Paul was fake.

Fake names, fake profiles, fake documents, fake wealth.

“There is no moral limit to Paul Carter,” Katherine told 60 Minutes.

The motive for his whirlwind romance of Katherine was a $300,000 payday which she was going to provide.

Brooklin Carter wasn’t dead.

She and her son (Paul’s son) were and are very much alive and came across pictures of his lavish engagement to Katherine on the internet.

Brooklin had met him in 2002 - his online dating profile said he was a childfree, single multi-millionaire and she quickly fell in love with him.

"He was the greatest lover, he was the greatest romancer, he was the smartest guy in the room. He seemed too good to be true," she told 60 Minutes.

They married the following year.

Little did she know he was a twice married father-of-three tradie from Melbourne.

He asked to borrow some money from her, and her wealthy father, while he waited for some inheritance to come through from a European relative.

"He’s showing me bank statements and a whole array of other documentation, which he produced fraudulently,” Brooklin said.

In 2014, as tension escalated in the family over the unpaid loans, Paul suggested they move to the United States - he sent his wife and son over first while he tied up business in Australia. That's when he met Katherine.

By this point Brooklin and her family were short more than two million dollars, but Paul had moved on to his new prey.

"He wasn't your average conman, he went to enormous lengths," Brooklin said. "There was always enough of the truth in his lies for it to be believable. He was a master at it."

The mother and son found out about Katherine when the little boy saw his dad in a photo.

"He walked into my bedroom and said who is this lady in the picture with dad?" Brooklin recalled.

"Can you imagine finding out that about your dad? He’s supposed to be your superhero and now he’s nothing to him. He’s just an embarrassment," Brooklin told 60 Minutes.

Meanwhile, back in Australia Katherine thought she'd found her Prince Charming.

"He was a magnificent beast - the knight that was going to rescue me and turn my life around," she told the show.

"But the Paul that I loved doesn't exist, he never did," she added.

He'd quietly charged their engagement party to her, the jewels he gave her were fake - and he ended up fleecing her of $300,000.

Katherine had told him her beauty salon was soon to be bought by the government. Once they were engaged, he convinced her to sign over legal rights to the salon so he could negotiate the payout on her behalf.

"There was a lot of stress involved in it and I was trying to run the business and deal with lawyers... and then there was Paul who was just such a rich multi-millionaire man. He wasn't going to be interested in my meagre $300,000 payout," Katherine told 60 Minutes.

Two weeks after their engagement party, Katherine received a Facebook message warning her that Paul's wife was still alive.

"I felt my reality go into a fog," she said.

She says he raped her when she confronted him about his lies.

"I think he realised that I was going to be the person that was going to shatter his facade. And I think that he was now pulling out all the stops to try and silence me," she said.

Brooklin says he also got violent with her when she ended their marriage.

"He threatened to kill himself and take me out as well. Now my son sleeps with a knife next to his bed and I sleep with a weapon next to my bed," she said.

Brooklin's divorce was finalised just six weeks ago, and somehow between now and then, Paul has married again - for a fourth time.

He's currently in Albany in New York, where he works as a self employed tradie, and lives with his new wife who was his divorce lawyer (who he couldn't afford to pay).

60 Minutes tracked Paul down and when they confronted him about lying about his wife being dead. he replied, "It was a mistake. Yes it was. I was going through a bad time with my then wife and it was just a mistake".

He also admitted that the European inheritance was a lie but became aggressive at the TV crew yelling, "I don't have any money dude, I didn't take any from f***ing anybody," as they continued to question his lies.

Katherine claims it's not just women he's conned.

"He has misled and manipulated church organisations, housing for the disabled. I mean he's the worst of the worst," she said.

If and when Paul comes back to Australia, he'll be arrested upon arrival and questioned over the allegations of rape.

Brooklin thinks he needs to go to jail for everything that he's done.

"Clearly no one is going to get their money back and I think he needs to be held accountable," she told 60 Minutes.