The court has heard how Pomphret called the emergency services and told them "a pack of lies", pretending he had just found his wife's body.
"My wife came to the stables a couple of hours ago and I've have not been able to get her on the phone so I have just come down to the stables and she is lying on the floor in a pool of blood," he reportedly told the emergency services operator over the phone.
"There is brain and blood everywhere, and it looks like she has had her head beaten in," he added.
According to prosecutor Gordon Cole, the husband also sent his wife a number of text messages after killing her, to give the appearance that he was looking for her. He texted her things like: "Where are you? All ok?", "Where are you? Getting worried.", "Is it the horses?" and "Bringing torches. D xx"
Police found the crowbar in a nearby pond.
The jury heard that Ann Marie suffered from a number of mental health issues and was on the autism spectrum. She was also undergoing treatment for cancer.
On the evening of the murder, Pomphret had gone to the stables to collect some tools. His wife took that to mean he was going to work all night whereas she'd expected they were going to have a "quiet night" together.
According to his lawyer, what followed was an argument during which Ann Marie "ranted and raved" and called her husband "useless". She then reportedly attacked her daughter Megan, 18, calling her a "fat slag" who was "out to get sex" that night.
"This is a case where a quiet man finally snapped," his lawyer Richard Pratt said.
"You may have little doubt in concluding this was a man who had completely lost his normal character and self control."
The victim's mother, Carol Buckley, said in a statement read to the jury that "David was an angel".
"He deserved a medal for putting up with Marie," she said. "I could not have wished for a better son-in-law or dad for Megan."
"Marie, I would describe as a Jekyll and Hyde character," Buckley's partner, Kenneth Crane, said, according to The Sun.
"She was like a volcano. She could erupt at any time without warning.
"I would describe David as a very quiet bloke. He would never talk or chat."
The trial continues.
