On most days during the affair, they began communicating around 9.30am. Usually Eamonn Lillis would text or phone Jean Treacy, but sometimes she would initiate the contact.

Often, they began with a blank text, to check whether the coast was clear of either Lillis' wife, Celine Cawley, or Treacy's fiancé. Eamonn Lillis was 51, Treacy 20 years younger than him.

On the morning Celine Cawley died, her husband did not initiate contact with his lover. At 9.44am, Treacy sent him a blank text. At that time, Lillis was at home in Rowan Hill, on Windgate Road in Howth.

Nine minutes earlier, a neighbour of the Lillis/Cawleys was awoken by the sound of a scream. Pauline Frazer says she heard a "high pitched scream", but she wasn't sure where it was coming from. She heard one, and then another about 30 seconds later. She thought initially it might have emanated from another neighbour's house where teenagers live, but she wasn't sure.

"It was very unusual, it was definitely somebody in trouble," she told the Central Criminal Court last week.

When Jean Treacy didn't receive a reply to her text, she sent another at 9.53am. "Keep ML if you can." This was a reference to the Mercedes Jeep owned by Lillis and Cawley.

"I sent a text at 10am asking him to bring the ML jeep, not from a seedy or sordid point of view, but just that when we were sitting in the front seat it would be more comfortable," she told the court last Wednesday. "The windows are tinted so you're not looking over your shoulder."

Lillis didn't reply. Within minutes of his mobile receiving that text, he was phoning the emergency services on the landline in a panic-stricken voice, explaining that somebody had attacked his wife, and she was unconscious and bleeding.

At 10.26am, Treacy send another SMS. She hadn't heard from her lover all morning and was growing worried. "Everything okay?" she wrote. By then, the emergency services and the gardaí were at the Lillis/Cawley home, attending to Celine Cawley.

Despite the best efforts of the emergency services, they were failing in all efforts to revive Cawley. Lillis was seated at the kitchen table, talking gardaí through how he had grappled with an intruder who had attacked Celine.

At 11.14am, Treacy tried communicating again. "Getting a bit worried now babe," she wrote.

Thrust into a living nightmare

Eighteen minutes before this text was sent, the emergency staff at Beaumount Hospital had declared finality on the life of 46-year-old Celine Cawley, pronouncing her dead.

Jean Treacy wasn't to realise it for another seven hours, but she had, as she related last week, just been thrust into a living nightmare.

Thirteen months down the line, those days must appear to Treacy to be from another world. When she was giving her evidence at the Central Criminal Court last Wednesday, she occasionally glanced down at Eamonn Lillis, who stands accused of murdering his wife. Lillis didn't notice. His eyes were glued to papers which he had before him. Treacy, for her part, remained composed through a testimony that parsed over the details of her affair with a married man.

On the first day of the trial, which has been in hearing for nine days, Lillis' lawyer said he was conceding there had been no intruder in the family home on the fateful morning. Lillis admitted he had lied and that he was the only other person present when Celine Cawley sustained the injuries that killed her. The principal cause of death was blunt-force trauma to the head, as a result of three blows. The couple had a 16-year-old daughter. Eamonn Lillis is pleading not guilty to murder.

On Wednesday, Jean Treacy was swept into and out of court in a manner usually reserved for criminals in the witness protection programme. She was driven in the back entrance designed for prison vans and staff. She was then taken up to the courtroom on the sixth floor by a lift reserved for prison officers and their prisoners.

In court, she was surrounded by plain-clothes officers. She left in the same protective cordon.

The court photographers, who gather at the main entrance, were enraged. As the 'other woman' to feature in the trial, her appearance was regarded as pivotal from a photographic point of view. That she is young and was expected to be attractive added to the fevered expectation of splashing her photograph across newspapers and television.

It wasn't to be. The garda investigators, who are led by Inspector Angela Willis, determined that Treacy was entitled to a modicum of privacy in a trial that has generated fevered interest among the public. (A question arises about the arbitrary nature of such decisions, but that is for another day.)

Each morning for the last week, spectators began gathering after 9am. An overflow room had been made available. Reports of evidence led many radio news bulletins through last week. At a time when human-interest stories attract far more attention than public-interest matters, the Lillis murder trial is top of the ratings. In such an atmosphere, amidst the frenzy and drama, the tragedy of an early violent death, bereavement, and families rent asunder, can get lost.

The affair began 16 months after Lillis began attending the Howth Haven beauty salon, where Treacy provided his weekly deep-tissue massage. They clicked in mid-October 2008.

When first questioned by the gardaí, she described Lillis as "refined and gentle", a bit of a dreamer and "somebody who wouldn't hurt a fly".

The end of the affair

The end of the affair came the day after Celine Cawley's death. "You need to concentrate on [Lillis' daughter] and what's happening to you," Treacy texted. "To do this I don't think we should have any contact till things have calmed down [for both our sakes]."

By then, Lillis was, as he put it himself "boxed in" to a whole series of lies about what had befallen his wife. The first person to whom he related what he now says is the truth was his daughter.

She went to Austria soon after her mother's death, attempting to escape what was "the world's worst Christmas" as she described it.

On her return, her father explained what had happened. "There was a fight and that was it," the daughter told the court on Thursday. "It was on the decking. He just said she slipped and they had a bit of a scuffle and that was it." She forgave her father for what happened, but she couldn't really forgive him for the lie.

"But I understand why he panicked to save him," she said.

The daughter, who cannot be named as she is a minor, was in another part of the court building, relaying her evidence via video link. She was dealt with in a sensitive matter, with both lawyers stepping cautiously through a teenage psyche that has been subjected to serious trauma.

In mid February, two months after the death of Cawley, her husband explained to his ex-lover what had happened. Treacy contacted him one night when she had a lot of drink on board. Lillis told her what happened, although Treacy says she didn't really want to know.

They met three times over the course of a few weeks. Then at the end of May, Treacy walked into her new job one day to find a package. Inside was a Tiffany diamond pendant, wrapped in paper that bore the lyrics of a Beyonce song. The gift was from her ex-lover. Treacy went to the gardaí and made a further statement.

On Friday, Lillis got the opportunity to tell the court how his wife had really died. For the previous eight days, he had been sitting a few feet from the witness box, listening, with his head bowed, as a series of witnesses reconstructed events and statements from around the time his wife died. Now he, by his own admission the only person present at the time, was going to tell it as he remembered it.

It began in the kitchen over a row about feeding the birds. "Celine called after me had I given the mealworms to the robins. I said I'd forgotten... we argued about it back and forth."

He walked out on the deck at the rear of the house. His wife followed him. Out of the corner of his eye, he saw her getting up off the ground. He presumed she must have slipped. On Friday, he suggested one of the three wounds to her head may be attributable to that fall.

Celine picked up a brick. "She thrust the brick at me. I said something rude to her and walked away." They began screaming at each other. "I went up to her, shoved the brick at her and said, 'why don't you shove this where the sun don't shine'." He pushed her back towards the sliding doors that led out to the decking. In his evidence, he speculated that this shove against the corner of the window could have contributed to another of the blows.

There was further scuffling. Celine bit his finger. She swung the brick at him, catching him on the face. He pushed her on the forehead. Both of them fell onto the decking. Celine Cawley hit her head again.

Then the row ended. Celine sat up. They decided to concoct a story about an intruder for their daughter to explain the injuries they suffered. Lillis asked his wife if she was okay.

He said she replied: "Yeah, yeah, f**k off and leave me alone. Go away. Go away."

Bloodstained jeans

He went upstairs to his bedroom, noticed how bloodstained his jeans and other items were. He put them in a plastic bag and into a suitcase which he deposited in the attic.

When he came back down downstairs, Celine was lying on the decking. He called her name twice.

"She didn't answer me. I knelt down beside her. I shook her chin and she didn't wake up. I didn't know whether she was breathing."

He maintained the agreed fiction about the intruder when talking to the emergency personnel and the gardaí. By the time he was told his wife was dead, he felt he was boxed into the lies.

"I'd never been in a fight in my life, especially in a situation like this," he told the court.

"My wife had died. I didn't want to accept it. I couldn't find any way of explaining to people what happened."

Lillis addressed the court in a low voice, his sentences often speeding up as he spoke. The jury foreman said some members were having difficulty hearing him. Once or twice, his voice faltered briefly, as he recalled details of the day his wife died.

He completed his direct evidence on Friday morning. His cross examination will continue on Monday before Judge Barry White and a jury of six men and six women.