She did not yell, or scream. She sat in silent disbelief.

Seven months later, her decomposing body was found on the muddy banks of a Brisbane creek..

Her unfaithful husband, Gerard Baden-Clay, sobbed as he told the Supreme Court in Brisbane on Monday of the day his wife discovered his long-term affair with his former employee Toni Cheri McHugh.

“I was at the office and Al called on my mobile and she just said, ‘we’ve got to talk’, and I knew, or I sensed straight away what it was about, so I suggested that we meet at the Indooroopilly McDonald’s,” Mr Baden-Clay said.

He paused, struggling to regain his composure in the witness box.

“We met in the car park. I think I arrived first and she drove in and parked beside me and I got out of my car and sat in the passenger seat of her car, which was Snowy at the time, I had indeed the Lexus. We name all our cars,” Mr Baden-Clay said.

“She just came straight out and asked me if I was having an affair with Toni and I said, yes I was, I had been.”

Mr Baden-Clay’s defence counsel Michael Byrne QC asked: “How did she react?”

“Just disbelief. She’d been told about it by her friend Wendy and she couldn’t believe it and then when I acknowledged it she was just in shock,” Mr Baden-Clay replied.

“She didn’t yell, or shout, or scream or anything, that’s just not Al. She got out of the car. She was just shaking her head.

“And she got out of the car and she sat on the little concrete curb thing next to the garden bed and I got out and came round and sat next to her.”

Mr Baden-Clay removed his glasses and wiped tears from his eyes.

“There wasn’t much said. She was just shaking her head, had her head in her hands. I think she might have been feeling physically ill, she didn’t vomit, but I think that might have been why she got out of the car,” he said.

“And after a little a while she said, ‘Do you love her?’ And I said, ‘No’. And she said, ‘You need to make a choice’.

“And it was just an absolute no brainer for me, I just said, I think I may have even said, ‘There is no choice, I want to be with you and the girls’.

“She said, ‘Well you need to end it now and I don’t want her ever coming back to the business or anything’, and I agreed …

“I put my arm around her shoulders. She shrugged them away.”

Mr Baden-Clay continued to sob, saying 'sorry’ to the courtroom.

He said he then called Ms McHugh, telling her he needed to speak with her straight away.

“We met at her unit. She was living at St Lucia,” he said.

“And I just told her that Al had found out and that I didn’t want to be with her, I wanted to be with Allison and the girls.”

Mr Baden-Clay told the court Ms McHugh flew into a violent rage.

“She was very angry. She said she couldn't believe it, she called me all sorts of names, that I was scum of the earth, that I ruined her, three years of her life. She yelled at me and screamed at me and she threw things at me,” he said.

“She said that she was never going to go back to work again. I didn't think to tell her that she wasn't able to anyway …

“I tried to calm her down, but I just couldn't. And she just yelled at me said, ‘Get out, I never want to see you again, get out’. And so I left.”

Mr Baden-Clay returned to his real estate office and proceeded to tell each of his staff members, one at a time, that he'd had an affair with Ms McHugh.

“I wanted the staff to know the facts straight from me, rather than hearing some sort of grapevine version,” he said.

Later that day, Mr Baden-Clay also told the principal of his daughters’ school about the affair, “just so that he was aware”.

“I didn’t want him hearing through the tuckshop rumour mill,” Mr Baden-Clay said.

“I wanted him to know that Allison and I were committed to each other and also to give him a heads up if there were any issues with the children that we could be made aware of it straight away.”

Mr Baden-Clay said he and his wife discussed his infidelity in more detail that evening, after putting the children to bed.

“Al at that stage said if I was committed to her and our relationship that in light of my breach of trust I needed to submit to some conditions that she had. And I agreed that I would do that, whatever she wanted, because I was committed to her,” he said.

Mr Baden-Clay said he was barred from going out at night and was required to hand his wife his phone each night so she could check his calls, texts and emails.

The court has previously heard Mr Baden-Clay and Ms McHugh rekindled their relationship around Christmas of 2011.

At the time, Mr Baden-Clay was confronted by his then-business partners Phil Broome and Jocelyn Frost, who asked if the affair had recommenced.

Mr Baden-Clay told the partners there were times he was sleeping with Ms McHugh “for the sake of the business”, because she was a top-performing saleswoman.

“I didn’t want her to leave the business and I didn’t want her to cause any dramas should the relationship end,” he told the court.

Mr Baden-Clay said Ms Frost relayed his remarks to Ms McHugh.

"She was quite justifiably very unhappy about that,” he said of Ms McHugh.

“And in fact I think at that time we were, the relationship, the affair was in some sort of a hiatus and we got back together for the sake of the business."

"So after that you and Toni got back into a physical relationship?" Mr Byrne asked..

"Yes," Mr Baden-Clay replied.

Mr Baden-Clay is accused of murdering his wife in their Brookfield home on April 19, 2012 and dumping her body in nearby Kholo Creek at Anstead.

He has pleaded not guilty to murder.

The trial continues.