A former cage fighter has denied being obsessed with his ex-girlfriend and told a jury he momentarily "lost control" when he killed her.
Andrew Wadsworth stabbed beautician Melissa Belshaw to death at her home in Billinge, Wigan, on 20 May after bingeing on alcohol and cocaine.
He told Manchester Crown Court he had become "overwhelmed" by a string of revelations about her sex life and killed her in "less than 10 seconds".
The 37-year-old denies murder.
The court has heard Ms Belshaw, 32, admitted to Mr Wadsworth days before she was killed that she had been receiving £1,200 a week for spending two hours with a "sugar daddy" but had previously denied being an escort.
Ms Belshaw also dismissed his persistent claims she had been sleeping with different people and angrily denied she had sex with a relative the day before she was attacked.
A post-mortem examination showed she sustained a series of "devastating" stab wounds delivered with severe force at her home on Upholland Road.
'No prolonged attack'
Giving evidence, Mr Wadsworth said he had "strong suspicions" about her sexual activities but had "nothing nailed on to prove it" until 20 May, when he said he was "overwhelmed" by her admissions.
He said she also "fully admitted" her part in setting up a robbery in which he broke his back and said another issue was about her "crying poverty… when she was earning a lot of money", adding he had given her "thousands" before they split up in December 2019.
He then denied a suggestion from Tim Storrie QC, cross-examining, that he had become "obsessed" with Ms Belshaw.
Mr Storrie asked if he had lost his temper with the 32-year-old.
"No, I didn't lose my temper," he replied, adding: "I lost control."
Mr Storrie then asked if because he had used alcohol and drugs, he had "believed in the nonsense and... decided to kill a woman who had irritated you for a long time?"
"No," he said again, adding: "In less than 10 seconds, Melissa had been stabbed to death. There was no prolonged attack."
He said if he had known what he was doing "for those few seconds, I would not have stabbed her in the first place".
Mr Wadsworth, from Wigan, also denies attempting to murder a neighbour of Ms Belshaw and making a threat to kill against Ms Belshaw's 13-year-old daughter.
The trial continues.