A primary school teacher charged with murdering her boyfriend was alleged to have made a diary confession about the killing, and detailed her "dark alter-ego".
Fiona Beal, 49, denied murdering her long-time partner Nicholas Billingham, 42, at their home in Northampton between October 30 and November 10 2021.
Prosecutors claimed she stabbed Mr Billingham in their bedroom, tied up and wrapped his body before purchasing items from B&Q and burying his body in their garden, and then repainting the bedroom to cover the blood splatters.
A notebook was recovered, from which entries were read to court by prosecutor Steven Perian KC, giving a "chilling account" of how she had planned and killed someone, the court heard.
Beal penned details of her "dark side" and explained how she hid a knife in a bedside drawer, the court heard.
Nursery apologises after child with Down's syndrome ‘treated less favourably’
Prosecutors claim she stabbed Mr Billingham in their bedroom (Northamptonshire Police / SWNS)Mr Perian added: "The police recovered a notebook from the place where she had been renting that detailed a chilling account of how she had planned and killed someone, but it did not contain the name of the person she had killed."
The notebook contained a reference to the 1991 film Thelma & Louise.
It read: "Everything changed last year. There's a quote from 'Thelma and Louise' that feels appropriate, 'Thelma: "You be sweet to them, especially your wife. My husband wasn't sweet to me.'
"I suppose I ought to explain what happened to get me to this point. My mental health had been deteriorating. Whenever he was cheating he would up the ante on belittling, moaning and criticising."
"I have to confess. Ok here goes. October 2021. He spat on me and threatened me during sex. I thought about leaving but the things he said and did fuelled my dark side - I call her Tulip22, she's reckless, fearless and efficient. Ruthless.
Forensic officers remove the body from a house in Moore Street in Kingsley, Northampton (Anita Maric / SWNS)
Nicholas Billingham whose remains were found buried in the back garden of a Northampton house (PA)"I started plotting as Tulip22 after he'd gone to bed. I could no longer sleep in the bed due to my breathing being too loud or I moved too much or I was snoring or etc. etc."
The court heard the notebook entry, which referred to 17 years of "him" being argumentative, mean, cruel, and belittling, continued: "I knew I couldn't let him get away with it. Halloween sealed it. He was vile.
"That night I planned. Covid rules meant I had a guaranteed 10-day isolation period from positive symptoms.
"I called [Beal's headteacher] on the Monday and said we'd tested positive and had symptoms. He went to work. Tulip22 smoked and planned. I'd planned it mentally so many times before.
Fiona Beal, 49, denies murdering her long-time partner Nicholas Billingham"I had a bath. I left the water in. I encouraged the bath with the incentive of sex afterwards.
Striking teacher forced to take a second job to pay bills ahead of mass walkout
"While he was in the bath I kept the knife in my dressing gown pocket and then hid it in the drawer next to the bed. I brought a chisel, bin bag and cable ties up too.
"I got him to wear an eye mask. It was harder than I thought it would be. Hiding a body was bad. Moving a body is much more difficult than it looks on TV."
Opening the prosecution's case at the town's crown court on Monday, Perian KC said Beal had written in a notebook that she believed Mr Billingham was cheating on her, and "had decided to kill him" by October 2021.
Jurors were told the notebook contained a claim that Beal had been spat on and threatened during sex and subjected to cruel and belittling treatment.
Forensic officers entry the property with a police dog in Moore Street, Kingsley, Northampton (PA)Alleging that Beal killed her long-term partner in their bedroom on November 1, Mr Perian told the court: "Nicholas Billingham whilst still in a relationship with the defendant had cheated on her with other women
"She (Beal) believed he was cheating on her again."
But instead of leaving him, Mr Perian said, Beal formed a plan on how and when to kill him, where to conceal his body, how to cover up and explain his disappearance to others, and how to explain her own absence from work when she killed him.
The prosecutor added: "The prosecution suggests from the evidence gathered it is very likely, she killed Nicholas Billingham during the evening of the 1st of November 2021 in their bedroom."
Having killed Mr Billingham, the Crown alleged she tied up and wrapped his body, buried it in the garden, and painted and cleaned the bedroom where the killing had taken place.
She is then alleged to have told others that Mr Billingham had left her for another woman, and to have used his phone to send messages to friends and work colleagues, pretending that he was still alive.
The court heard Beal was found by police in March last year at a lodge near Kendal in Cumbria, after suffering superficial wounds and writing "what read like a suicide note".
She was then taken to the local hospital and detained under the Mental Health Act.
A pathologist concluded that the cause of Mr Billingham's death was a single stab wound to the right-hand side of his neck, which cut through the jugular vein.
Records showed Beal, who worked at Northampton's Eastfield Academy as a Year 6 teacher, was absent from work between November 1 and November 12.
Beal denied murder and the trial continues.