A security guard told a court his estranged girlfriend's death by stabbing began with an accident: he had been holding a knife in order to kill himself when she fell onto it.
Poon Man-sum, 32, who denies murdering 24-year-old Law Yuk-yu, told the High Court he had intended to commit suicide at Law's Tai Po flat after she refused to get back together with him.
Poon said Law's response to the threat was: "Don't be childish. Please be more mature." Law also told Poon not to use the prospect of his death to intimidate her, the court heard. If he wanted to die, he should do so somewhere other than her home, she told him.
"At that moment, I thought, 'How could she be so ruthless?'" Poon said. "I spoiled her and was never unfaithful to her."
Angered by her response, Poon followed Law to her bedroom and tried to grab her phone from her hand.
He tried to pull her onto the bed, but she fell onto the knife he was holding.
Poon said Law's back was injured and she cried out loudly. He tried to comfort her and told her he would call an ambulance.
"She cried in a crazy way and grabbed hold of my genitals," Poon said. In intense pain, he stabbed her a number of times. Believing she had died, he said, he decided to stay with her body that night.
He admitted using Law's mobile phone to reply to messages from her sister. "I only wanted to stay with [Law] and did not want her to be disturbed," Poon told the court.
Poon earlier admitted the attempted murder of love rival Chan Tai-wai, 20, at the Tung Chung housing estate where he, Chan and Law worked.
He stabbed Chan on November 29, 2012, a day after Law's death.
He read messages between Chan and Law on the latter's phone and told the court Chan had destroyed his relationship with his girlfriend.
"It led me to want to do one last thing in my life: to kill [Chan] and then commit suicide," Poon told the court.
Cross-examining Poon, prosecutor Nicholas Adams asked him whether he wanted Chan to accompany Law into the afterworld as a ghost.
"I would commit suicide and go to the afterworld as well," Poon said.
The trial continues today before Mr Justice Alan Wright.