When Gerard Baden-Clay turned away from his wife and into the arms of several lovers – one, in particular – he could not have foreseen where his infidelity would lead him.

He murdered his wife.

He robbed his three young daughters of their mother’s love and care.

And he’s been left to contemplate years behind bars for his sins.

All for what? If you believe Baden-Clay’s admissions in court, for nothing beyond the basic human desire for sexual gratification.

He made much of that desire as he attempted to convince a Brisbane jury that he did not kill his wife Allison in large part because he’d fallen in love with one of his mistresses Toni McHugh.

He admitted to a string of affairs after his once strong, confident and energetic wife spiralled into depression, and the intimacy in their marriage vanished.

In 2006, Baden-Clay began a month-long affair with a former colleague.

“I just wanted sex,” he sobbed at his Brisbane murder trial.

“Allison and I hadn’t had any sort of physical intimacy for years. It’s not an excuse but that’s why.”

But it was the affair he began two years later with Ms McHugh, a sales agent from his real estate business, that put Baden-Clay on the path to destruction.

The mother-of-three was herself in a committed long-term relationship when she joined Baden-Clay’s growing Brisbane agency.

The pair were working back late one night when they first consummated their relationship.

That office encounter was the start of a torrid, on-off affair that spanned almost four years and continued even after Allison found out about her husband’s betrayal.

The portraits Baden-Clay and his mistress painted of their affair could not have been more different.

Ms McHugh told Baden-Clay’s trial of a relationship underpinned by mutual love, and of his repeated promises to abandon his old life for a new one with her.

In emotional testimony she said he’d told her many times that he loved her, and the court heard how, in the weeks before Allison disappeared, he even set a deadline to abandon his marriage.

“I have given you a commitment and I intend to stick to it – I will be separated by 1 July,” he wrote in an email to Ms McHugh on April 3, 2012.

That was two and a half weeks before Baden-Clay called police to report his wife missing from their Brookfield home, and about a month before her badly decomposed body was found on the bank of a nearby creek.

Ms McHugh told too of her clandestine meetings with her lover, as often as four times a week, and how the affair was common knowledge among their colleagues.

The picture Baden-Clay painted bore no resemblance to Ms McHugh’s account.

In words that must have been devastating for his former lover to hear, he told the court he’d never loved her and that as their liaison continued – even after his wife found out about it – he was working hard at home to repair his marriage.

Allison was his priority and his future, he told the jury. All he really wanted from Ms McHugh was sex, and his empty professions of love and a life together were designed to ensure he continued to get it.

“For me it was only a physical relationship. I didn’t want anything more,” Baden-Clay testified.

“I often said to her things in order to placate her, what she wanted to hear …”

As the affair rolled on, Baden-Clay had convinced his wife his infidelity was over. The couple had resumed their sex life, and they were following the advice of their marriage counsellor, including a suggestion the couple spend 15 minutes a day letting Allison “vent” her feelings after she found out about his infidelity.

The court heard Allison had done exactly that on the night before she disappeared.

Baden-Clay told police it was a constructive discussion about some “difficult things”, but they did not argue and everything had been fine when he went to bed, confident their marriage was on the mend.

On that same evening, the last time Allison was seen alive, there was another conversation too.

Ms McHugh had called Baden-Clay, and in her own words “lost it” at him, after learning she and Allison might cross paths at the same real estate conference the following day.

“You need to tell her,” Ms McHugh told Baden-Clay in a rage.

He didn’t. That would have alerted his wife about his ongoing contact with Ms McHugh.

The court also heard Baden-Clay and his mistress spoke on the day he reported Allison missing. He sounded distressed and told her to “lay low”.

In a later conversation, he told her: “I need you to know that I don’t know what’s happened here. I need you to know I love you.”

Then in a final, secret meeting in June 2012, days before Baden-Clay was charged with murder, he told Ms McHugh she’d have to fall in love with somebody else.

“He suspected that things weren’t going to be looking good for him,” Ms McHugh told his trial.

He was right. That was the end of the affair, and the next time the lovers saw each other, Ms McHugh was giving evidence at his committal hearing.

Precisely what role their illicit relationship played in Baden-Clay’s decision to murder Allison may never be clear.

But in convicting Baden-Clay of murder, the jury has accepted the prosecution’s argument that it was a motive in a crime that’s left three young girls to grow up without their mother.

Allison’s parents have lost their beloved daughter and are now tasked with raising those girls.

Toni McHugh’S life has been turned upside down in the two years. She’s suffered the embarrassment, and no doubt some degree of public judgment, of being “the other woman”.

Baden-Clay himself has lost it all. His wife, at his own hands, the relationship he once had with his children, his business.

And his freedom, for at least the next 15 years.