Theresa Mulvihill says her husband, Paul, put a pillow over her face and said, "It's not you, it's her" just days before he allegedly killed his former mistress.
Mr Mulvihill, 46, is charged with the murder of Rachelle Yeo, 31, by stabbing her to death inside her North Curl Curl unit about 8pm on July 16, 2012.
On Thursday, Mrs Mulvihill told a NSW Supreme Court jury her husband rang her about 10pm that night and said, "She's gone."
Mrs Mulvihill said she replied, "What are you talking about?"
When he repeated the words, "She's gone", Mrs Mulvihill said, "Rachelle."
Mr Mulvihill said, "Yes."
Mr Mulvihill has pleaded not guilty to murder, claiming he stabbed Ms Yeo in self-defence after she attacked him.
Mrs Mulvihill said that, on the morning of Ms Yeo's death, she rifled through her husband's suitcase as he told her he was flying to Melbourne for his work at pharmaceutical company Sanofi-Aventis.
She found a receipt from the department store Big W for a "hoodie" for about $19 and a white plastic chain.
Mrs Mulvihill said she found the receipt "very bizarre" because she does not shop at Big W and her husband did not wear such clothes.
Mr Mulvihill's barrister, Kate Traill, said Mrs Mulvihill mentioned the receipt when interviewed by police investigating Ms Yeo's death but did not mention the chain.
Under cross-examination, Ms Traill accused Mrs Mulvihill of lying about the chain, saying she made it up to help the Crown case against her husband.
Ms Traill said it was in Mrs Mulvihill's financial interest if her husband was convicted, because if he was imprisoned she would receive 100 per cent of the couple's estimated $2 million asset pool after their divorce.
Mrs Mulvihill vigorously denied the suggestion, saying she lied to police when giving a statement in December 2013 because, "I was trying to protect Paul at the time because we were getting along quite well.
"He is the father of my children. It is not in my interest for him to be in jail for the rest of his life," she said.
Ms Traill also suggested Mr Mulvihill did not attempt to put a pillow over his wife's face, but tried to get into bed with her and brought his own pillow with him.
Mrs Mulvihill disagreed.
"It wasn't heavy but he had it over me and held it there."
The next day she said Mr Mulvihill called her from Sydney Airport, saying, "There was police everywhere."
"He said he was trying to get on a flight but that there were a lot of police around, so he said 'I’m not going to stay here,' " Mrs Mulvihill told the court.
Johan Duflou, the chief forensic pathologist at the Department of Forensic Medicine, said that, in his opinion, Ms Yeo was stabbed in the neck and survived for a few minutes before being stabbed in the heart.
Under cross-examination, Professor Duflou conceded it was possible Ms Yeo received the chest wound first, but he said it was unlikely.
He said at autopsy there was no evidence Ms Yeo had been strangled with a white plastic chain.
He said Mr Mulvihill had "very minor injuries’’ and Ms Yeo had "very serious injuries’’.
The trial continues.
- with AAP