A man accused of murdering his pregnant ex-wife with a crossbow claims he had only wanted to confront her new partner about allegedly forcing his daughter to live as a Muslim.

Ramanodge Unmathallegadoo, 51, killed 35-year-old Devi Unmathallegadoo at the home she shared with her husband, on the morning of 12 November 2018. The Unmathallegadoos’ marriage had broken down in 2012 and she had since married Imtiaz Muhammad.

Unmathallegadoo allegedly became obsessed with getting revenge on the couple, and built a cache of weapons costing thousands of pounds.

The defendant, who had been sleeping rough after losing his job as site manager at Newham general hospital, allegedly spent the night before the attack sleeping in the victim’s garden shed, armed with two new crossbows, bolts, a hammer and a knife in a homemade sheath.

The Old Bailey heard that when Muhammad went to put an item in the shed, Unmathallegadoo, known as Ram, chased him into the house armed with his two crossbows and a knife.

The defendant shot his ex-wife in the abdomen as she attempted to flee upstairs at the family home in Ilford, east London. She sustained catastrophic injuries and died a short while later. Her unborn son was delivered by emergency caesarean section and survived.

Giving evidence, Unmathallegadoo claimed he had only wanted to confront Muhammad for allegedly forcing his 12-year-old daughter to live as a Muslim.

He explained how he had spent more than two hours hoisting all his equipment over three garden fences and into the victim’s garden shed on the evening before the killing.

“I only wanted to confront Imtiaz over the treatment my daughter was going through – he would force her to pray in the Islamic faith and she didn’t want to. She was forced to eat halal food and she was forced to wear non-European clothes.”

Devi Unmathallegadoo, 35, died from catastrophic injuries. Photograph: Metropolitan police/PA

The court heard Unmathallegadoo was barred from contacting his children by a restraining order, but claimed he had spoken to his daughter on her way to school. “I could sense her saying, ‘Daddy, help’ – you could see it in her face and in her eyes,” he said.

When asked why he had not just knocked on the door to talk to the family, Unmathallegadoo said: “I couldn’t. I was scared of Imtiaz as well. He was a big man. The crossbows were basically a deterrent so I didn’t get attacked by Imtiaz.”

He told the court how he felt about his wife having two more children with Muhammad, and her pregnancy. He said: “It was nothing to do with me. I was past that. That’s her life.”

Describing the attack, he said: “I wanted to confront [Muhammad]. I wanted to talk to him but he just ran without stopping.”

Unmathallegadoo said Muhammad and the victim had tried to run upstairs and that he had been aiming the crossbow into the wooden bannister rail.

The defendant said he had been looking for the safety catch when he accidentally fired the crossbow. He told the court he wanted the safety catch to be off, so he could fire it, claiming he had planned to shoot into the bannister rail to make a loud noise and scare the couple.

“As soon as it was fired I felt really helpless, as soon as it discharged I went to the kitchen to get the other one.”

Unmathallegadoo said the first time he realised anyone was hurt was when he heard one of the children on the phone to the emergency services.

When asked how he felt about killing the victim, he replied: “I feel really, really distressed at the thought that she got hurt because of me – I feel bad for the children, for Imtiaz himself and his children.”

He denied stockpiling weapons with the intention of killing his former partner, claiming he had bought them to take to his native Mauritius so he could go hunting with his brother. The court heard the crossbow cost more than £1,000.

The defendant, formerly of Ilford, has denied murder and the attempted destruction of an unborn child.