A woman has been jailed for four years for killing a 63-year-old school dinner lady in Aberdeenshire.
Michelle Wallace, 30, who had a history of mental health problems, regarded Helen Hewer as her substitute mother.
Last month she admitted culpable homicide by stabbing the mother-of-two to death after an argument in Greens Road, Newmachar, in July.
At the High Court in Dumbarton, Judge Lord Pentland told Wallace she acted "recklessly with tragic consequences".
He said: "It is clear that you have had many difficulties in your life since childhood.
"But none of the background, to which reference has been made, can possibly serve to excuse your conduct on 19 July this year when you stabbed and killed the lady who had taken you in and apparently looked after you.
"No sentence that I impose can undo the devastating effects of your loss of self-control."
Mrs Hewer was found on the bedroom floor of her home after Wallace dialled 999.
Wallace later told police: "It was me", and added: "I didnae mean to do it."
Defence QC Frances McMenamin said Wallace had stopped taking her medication just weeks before the fatal knife attack.
The defence counsel said Wallace's life had been blighted by family problems and she had been taken in by Mrs Hewer, Wallace's mother's cousin.
There was "an emotional bond" between the two women and Mrs Hewer's death had left Wallace devastated at her actions, she said.
The QC said: "This was a woman who had mothered her in a way her own mother hadn't."
A row "got out of hand" on the day of the killing, the court heard.
Advocate depute Kay Harper said that, when questioned by police, Wallace described an argument about a man in Mrs Hewer's life.
The prosecutor said: "When the argument got out of hand, the accused said that she grabbed a knife which was lying on the bedside cabinet and stabbed the deceased."
Wallace's blow penetrated her victim's liver and heart.
When police caught up with blood-stained Wallace in a nearby park she told them: "It was me who called you on 999. I just saw blood and freaked."
Wallace was initially accused of murder but the charge was reduced to culpable homicide.
Lord Pentland also imposed an additional three years sentence, during which Wallace will be under supervision and can be recalled to prison if she reoffends.