The man died in Royal North Shore Hospital from his injuries, including stab wounds to his jaw and leg.
Police said Xian Peng, 48, had returned from China for a visit and was at the home of his former de facto Jian Chen in North Ryde on Tuesday night.
Police allege Chen served her de facto soup laced with sleeping tablets.
Mr Peng then fell asleep on the couch where he was tied up before allegedly being stabbed a number of times and his penis severed.
It is alleged Chen rang triple-0 and ambulance officers arrived at the Ruse St home and called police. Chen, 47, was taken to Ryde police station and charged with grievous bodily harm with intent to murder.
Chen, who owns a $1 million home without any mortgage, appeared before Ryde Local Court on Wednesday and was refused bail. Mr Peng died at 6pm that day.
Mr Peng was due to return to China yesterday.
Police are now expected to upgrade the charges to murder when the woman appears before Burwood Local Court on February 23.
Chen lived at the Ruse St property with her two sons.
The oldest, a teenager, was from her first marriage and the youngest was Mr Peng’s son.
She moved into the double-storey brick house about 12 years ago and opened a seafood import business, Ocean Meats Australia, in July 2009.
Most residents describe Chen as a good but reserved neighbour and knew little about her life. They waved at her as she passed in her black Jeep in the street, and often saw trucks making business deliveries to the house. She kept the seafood in a large freezer in the backyard.
Chen’s brother, his wife and their son visited at Christmas and the family celebrated with lunch at the home.
Other Chinese women were also regularly seen at the house.
“She got the groceries, she picked up the kids, she was in the garden, but there was nothing out of the ordinary with her,” one neighbour said.
“I never saw the kids but I know they were there because I could hear them talking and playing kid’s music.”
Another said: “She was a nice woman, she waved hello and goodbye, but that was it.”
Many were not aware of any trouble at the house until police knocked on their door on Wednesday morning.