Valerie French Kilroy's husband described to gardaí how he "waited in the long grass" at night for his wife to return home from a meeting with friends before silently carrying out a "dark and frenzied" attack on his "soulmate".
James Kilroy, who admits killing his wife at their rural Co Mayo home, denied to gardaí that he had used a ligature and said it was "just his hands", telling detectives that she was still alive when he left her.
He added: "She was talking when I left her, I had to get out, she morphed into a zombie".
The Central Criminal Court jury also heard Ms French Kilroy was his "first real love", that she had shown him "the brighter side of life" and they once shared a "budding romance".
"It was love at first sight, she was everything," he added.
Earlier, the Chief State Pathologist told the murder trial that the mother of three and occupational therapist died from ligature strangulation, blunt force trauma to the head and a stab wound to the neck.
Park ranger James Kilroy (49), with an address at Kilbree Lower, Westport, Co Mayo is charged with murdering Valerie French Kilroy (41) at their home on a date unknown between June 13 2019 and June 14 2019, both dates inclusive.
He has pleaded not guilty by reason of insanity.
Patrick Gageby SC, defending Mr Kilroy, has made a number of formal admissions to the court on behalf of his client including that he killed his wife Valerie.
Evidence has been given that gardai found Valerie's body lying in the foetal position on the floor of a campervan with her bloodied hand protruding outside the sliding door and a child's car seat over her face.
Detective Garda Declan Sweeney from Castlebar Garda Station told Michael D Hourigan BL, prosecuting, that Mr Kilroy was interviewed on four occasions.
At the outset of the first interview on June 15, 2019, the accused said he went to army cadet school as he didn't want to be bullied.
He tried to join the army at 17 years old but couldn't become a "regular soldier".
"The dream was to save the white rhino," he said, and later went on to say that he did gamekeeping.
The accused said he remembered his "first exposure" to cannabis and "smoked weed" in college as it was cheaper than drinking.
He and his friend were called "The Doobie Brothers", he recalled.
He talked about "doing speed" and his first introduction to class A drugs, as well as getting "into acid" and ecstasy.
He also said he did "magic mushrooms" in 1998.
In 1996 he had a row with his employer who "pushed" him over money.
"I got up thinking I was going to kill him but I just got up and thought fuck him".
In 2000, the accused said he moved to Scotland where he went to "many parties" in Edinburgh and got a job shooting red deer.
"That was the first and only time I took cocaine".
Soon afterwards Mr Kilroy said he got a job in Connemara National Park.
He later went to a party in Kildare, took acid and said "that night changed my life".
He said he was having "bad thoughts and suicidal thoughts" around this time.
The defendant said he would always write letters to his "first real love" Valerie.
He said they met on holidays when she was 18 and he was 21 years old. "She showed me the brighter side of life.
It was love at first sight, she was everything".
Mr Kilroy said he was in the garda station to tell the truth about his life with Valerie and that they had a "budding romance" getting to know each other.
He said Valerie decided to come to Mayo in 2004 and "what it did to her was indescribable".
The accused said he proposed to her in 2007 and that they shared "good times and good parties".
"I loved her, she loved me, where she went I went, she was my soulmate".
Mr Kilroy said they didn't have sex until they were married and he had to get "checked out" later.
"I was the problem, not producing any sperm". The couple looked at adoption but had their first child in 2013.
The accused said he grew two cannabis plants at home to help his anxiety but had been feeling strange for quite some time.
He said Valerie was "always dead against drugs".
He added: "I love Valerie and she loves me; we hold hands at the table every morning and say prayers".
Mr Kilroy described looking at pornography and playing video games.
Detectives asked the defendant how one killed someone they love so much. "I'll do my best to explain," he said.
In his second interview, the accused said Valerie was "pissed" on June 13 as he was "being an ass".
When she was out meeting her friends that evening he took a bath and cut his hair.
He said he jumped out the back window when it was getting dark and "waited in the long grass".
He jumped into a bonfire which wasn't lit at the back of the house.
He said he heard a car and that it was Valerie.
"I heard her say 'James is that you'. I didn't say anything. I ran, pushed her up against the door, slit her throat."
Mr Kilroy described it as a "battle" and said Valerie was delivering "strong kicks and punches".
He said there was "blood everywhere". "I was nasty, killed her with my bare hands, felt the dead were going to get me and she was the leader".
He said he went back into the bathroom after killing Valerie, emptied the bath and was eating leaves.
He said he slit her throat as she came out towards the shed.
He said the knife he used was a "black serrated 12 inch bendy knife" and that he wasn't defending his actions but the blade broke and he was "disarmed".
He said he smashed Valerie's head off the ground. When asked why, he said he was "just in the zone and had no bearing". "It was surreal, something you do in a comic book".
Asked if he knew the impact of his actions, Mr Kilroy said: "Yes, I was just a stone cold fighter. I'd no plan to kill my wife".
When the officers asked him how many times he had struck Valerie with the knife, he replied: "From the throat down to the belly, it was a frenzy".
Mr Kilroy said he hadn't taken any intoxicants that day and that he had been off alcohol and cannabis that whole week.
He said he tried to suffocate Valerie, that there was nothing to stop him and it was "black and nasty".
"I killed her with my bare hands, I knew I fucked up".
He said he was going to do all the commandments; "murder done, adultery next".
Mr Kilroy drew a rough sketch of his house at Kilbree Lower and showed gardaí where the assault took place.
He said there was a bit of friction on the afternoon of June 13 as Valerie just said "dinner".
He said there was no animosity between them, the odd 'spat' but that they didn't row very much.
Asked if he had ever gotten physical in the past, he said "no never". "I never raised my hand to anyone".
The accused was asked to draw a sketch of the knife he had used to assault Valerie. After drawing it he remarked: "I'm actually surprised how accurate that drawing is".
When shown a knife and asked if that was the one he had used "to murder" Valerie, he said it was.
Gardaí put it to the accused that there was a ligature mark on the deceased's neck.
"I didn't use a ligature or anything, I just used my hands," he replied. He said it was "dark and frenzied".
Asked how Valerie had "ended up" in the campervan, he said he put her in there, closed the door and walked away.
When asked about the significant wound to her hand, Mr Kilroy said he couldn't look at it.
Gardaí suggested to the accused that it seemed to have been a frenzied and sustained attack on his wife.
The trial continues on Tuesday before Ms Justice Mary Ellen Ring and a jury of ten men and two women.