A nurse who performed on Britain's Got Talent was stabbed more than 70 times by her former soldier boyfriend in an "utterly terrifying" attack, a court has heard.
Simonne Kerr, 31, "did not stand a chance" when Desmond Sylva came at her with an 8in (20cm) kitchen knife, the Old Bailey heard.
Sylva, who served with the Royal Regiment of Fusiliers in Iraq and Kosovo, had been admitted to hospital with suicidal thoughts and threatened to kill himself or someone else the night before, jurors at the Old Bailey were told.
The 41-year-old Jamaica-born defendant has admitted manslaughter but denies murder, claiming his depression impaired his mental function.
However, the prosecution allege that he attacked the Guy's and St Thomas' nurse simply because he "lost his temper".
Opening his trial, prosecutor Oliver Glasgow QC said Ms Kerr was last seen leaving the hospital where she worked on August 15 last year, heading to Sylva's flat in Clapham, south London.
At lunchtime that day, Sylva telephoned his brother to say he had just murdered his girlfriend before alerting emergency services, the jury was told.
In a 999 call played in court, Sylva said: "Can I have police please? I've just committed a murder.
"I'm ex-Army and I've got lots of mental health issues."
Asked why he had done it, he said: "She's just get on my nerves, man, trying to fight me and take my money so I had to defend myself (sic)."
Police found Ms Kerr's body wrapped in a blood-soaked duvet, suggesting she had been attacked while lying in bed, jurors heard.
Mr Glasgow said: "Her throat had been slashed and she had been repeatedly stabbed to the right side of her face and her neck.
"Desmond Sylva had used a kitchen knife to inflict more than 70 wounds to her body and, despite her efforts to fight him off, she was clearly powerless to do so."
Afterwards, the defendant initially told police he had acted in self-defence during an argument and claimed to have partial amnesia.
But Mr Glasgow said: "What is obvious is that Simonne Kerr did not stand a chance.
"The last few minutes of her life must have been utterly terrifying: repeatedly stabbed by the man who was supposed to care for her but who in the end simply butchered her and then tried to blame her for what he had done.
"The question that you will have to determine is why he did what he did.
"He chose to pick up a knife and he chose to use it again and again to stab Simonne Kerr at a time when he was not acting in lawful self-defence and did not need to defend himself from her.
"His depression neither explains nor justifies his actions and what happened was that his anger got the better of him and he simply lost his temper."
Sylva completed two tours in Iraq and one in Kosovo before being discharged from the Army on medical grounds.
Since then he has been given treatment on a number of occasions and diagnosed with bipolar disorder, post-traumatic stress disorder and depression, jurors heard.
By the time of the killing, he was working as a security guard in Canary Wharf and had been prescribed medication for his depression.
Sylva's family knew about his struggle with depression and he was briefly admitted to Chelsea and Westminster Hospital after telling his mother he was feeling suicidal on August 9 last year.
The day before the killing, the defendant allegedly told his brother, Damian Sylva, that he was going to kill himself or someone else.
After speaking for a long time, Sylva appeared to calm down and said he was getting ready for work, the court was told.
When Sylva called his brother to say he had "murdered his girlfriend" the next day, it was the last thing he expected to hear, Mr Glasgow said.
The Old Bailey trial is expected to go on for up to 10 days.