A man accused of murdering his heavily pregnant estranged wife with a crossbow has told a court he only used it as a "deterrent".
Ramanodge Unmathallegadoo, 51, shot his wife Devi, 35, at their east London home in November 2018 after their marriage broke down, the Old Bailey has heard.
He said he loaded two crossbows to protect himself from her new partner Imtiaz Muhammad.
He denies murder.
Giving evidence, the defendant described seeing Mr Muhammad in the garden from the shed and chasing him through the house towards the stairs.
He said he took the crossbows with him "only as a deterrent because I didn't want to be intimidated physically by Imtiaz".
He told the court he dropped one of the weapons in the kitchen because he could only aim one at a time.
"Devi and Imtiaz were on the stairs. I just wanted them to stop. I thought if I hit the banister they would hear the noise and stop," he said.
"While I was checking the safety catch, the next thing I know there was a bang."
He admitted he had not used the word "stop" to the couple.
"When the crossbow had been discharged, I felt defenceless so the next thing I did was go back to the kitchen and get the other one," he added.
The court heard the defendant did not realise Mrs Unmathallegadoo had been hit.
The crossbow bolt penetrated her body, causing "catastrophic" internal injuries, including piercing her heart, jurors have previously been told.
Medics were unable to save her but her baby was delivered by emergency Caesarean and survived.
Mr Unmathallegadoo had been stockpiling weapons and equipment for more than a year before the killing, the trial has heard.
When his cache of weapons was discovered by chance, he allegedly set about replacing it within days.
The defendant also allegedly carried out surveillance on the home in Applegarth Road, where he had previously lived with his estranged wife.
The trial continues.