Accused murderer Paul Mulvihill says his former lover wanted to stay together despite their affair being exposed.

Accused murderer Paul Mulvihill says Rachelle Yeo wanted to continue their affair even after she became engaged to another man and her own mother asked them to split.

Mulvihill, 46, is accused of stabbing his former lover to death in her home in Sydney’s north in July 2012, after they began a romantic affair while both working for Sanofi Aventis pharmaceuticals.

A NSW Supreme Court jury has heard Ms Yeo “basically lost all her blood” in her North Curl Curl apartment after Mulvihill stabbed her with a knife.

Taking the stand for the first time during his trial, Mulvihill told the court he suggested they end the affair in August 2011 after she became engaged to her boyfriend, Paul Maher.

“She said to me, ‘Paul, I don’t want to stop seeing you … I want to continue our relationship,’” he told the court.

“I said to her that I wasn’t so sure it was a good idea.”

During that conversation, Mulvihill said Ms Yeo said she loved him for the first time and they both decided to continue the relationship.

But the following January, Mulvihill said he came home from work one day to find bags packed with his clothes and thought his wife Theresa “must’ve been doing a bit of a clean-up”.

Upon finding a set of print-outs of text messages between himself and Ms Yeo lying on the dining room table, he realised his wife had discovered the affair after unlocking his phone.

But when he next saw his lover, they both again decided to keep the affair going, Mulvihill said.

“Rachelle said ‘Paul, I’m sorry for what’s happened, no one was meant to get hurt,” he said.

“The bottom line was … we mutually decided we would continue to see each other.”

After the infidelity was exposed, Ms Yeo became “anxious and nervous” that any call she received from a private or blocked number was Mrs Mulvihill, he said.

Mulvihill said he had started to have grave doubts about the future of the relationship after Ms Yeo made plans to move from Brisbane to Sydney because he wasn’t sure he wanted an interstate relationship.

The court had heard previously that Mulvihill was based on the Gold Coast at the time.

About now he took a call from her mother Kathy, who urged him to end it.

“The first thing she said was, ‘Paul, I know you and Rachelle love each other very much’ but she didn’t feel it was a very good idea we continue,” he said.

When he told Ms Yeo, she’d implored him to let her “sort out the issue with Mum”.

“Rachelle said to me, `I don’t want you to stop seeing me,’” he said.

Mulvihill has pleaded not guilty to her murder and says he was acting in self-defence.

The trial continues.