A jury has been told that a 50-year-old woman became hysterical, stripped naked and threatened to cut off her 31-year-old lover's penis after he ended their relationship.
Jacqueline Carol Taylor, of Glenhouse Mews in Eglinton, Co Londonderry, denies threatening to kill, attempting to wound and assaulting Wayne Simpson.
The offences are alleged to have occurred in her then Old School Field flat in Drumahoe in the early hours of October 27, 2010.
A prosecution barrister told the jury of five women and seven men that Taylor and Simpson were work colleagues in Tesco at the time of the alleged offences.
He said they had been involved in "a pretty intense relationship" which was ended by Simpson.
The barrister said Ms Taylor was "very, very upset" when Simpson told her of his new relationship with a woman called Sharon.
He said that on the night before the offences, the defendant contacted Simpson saying she wanted to discuss their relationship.
"She said if he did not, that two carloads of men would call at his house, pull him out of his bed and kneecap him," the barrister said.
He told the jurors that when Simpson arrived at the defendant's flat and went into her bedroom, she became very violent. She asked Simpson to stay with her until she fell asleep but, when he refused, the defendant reacted violently.
"Jacqueline Taylor went mad. She jumped out of bed and she stripped naked.
"She said she was going to slit Sharon's throat," the barrister said.
He alleged that Ms Taylor then went to the kitchen and returned with a knife with an eight-inch long blade.
She started swinging the knife at Simpson.
"She said she was going to stab him, pull down his trousers and cut his penis off when he was dead," he told the jury.
"She then rang 999 and told the police she was being attacked by Simpson. When the police arrived at 12.40am, they saw Jaqueline Taylor standing outside the front door of the house naked. She was absolutely naked and had blood on her body and on her left hand," he told the court.
After she was arrested, the defendant was taken to Altnagelvin Hospital where she received three stitches for a cut to her hand, the barrister added.
The trial continues.