A man pressed a blanket over the mouth and face of his girlfriend to calm her down when she became hysterical after they had both taken methamphetamine, or Ice.
Jackson Lim Hou Peng, 41, was worried that her shouts would make neighbours call the police.
The Singaporean odd-job labourer ended up suffocating Ms Tran Cam Ny, 32, a Vietnamese KTV lounge performer and hostess, on the morning of Nov 20, 2014.
Yesterday, Lim was sentenced to a total of 9-1/2 years' jail and three strokes of the cane after he pleaded guilty to one count of culpable homicide without intention to cause death and one count of taking Ice.
He was sentenced to 4-1/2 years on the homicide charge and five years' jail and three strokes of the cane on the drug charge, which is the minimum for third-time abusers.
In sentencing Lim, Justice Tay Yong Kwang said: "This case demonstrates how taking illegal drugs can sometimes lead to very sad and fatal consequences which were never intended."
The High Court judge advised Lim not to go back to drugs again after he is released from prison.
The court heard that Lim and Ms Ny were in a relationship while married to other people. Lim is estranged from his wife who lives in Vietnam, his lawyer told the court.
On the night of Nov 19, 2014, Ms Ny stayed over at Lim's rental flat in Ang Mo Kio and called two of her friends to join them. Lim started smoking Ice and she joined him.
Not long after, she started crying and quarrelling with Lim, accusing him of spending the money that she gave him on other women.
He left the bedroom to take more Ice but she continued berating him. The couple exchanged blows before they were separated by her friends, who pulled her into the room.
When she continued shouting hysterically, Lim went into the room and slapped and punched her. At this point, her friends left the flat.
Ms Ny did not stop shouting even after Lim pinned her down, sat on her chest and hit her repeatedly. To stop her from shouting, he pressed a blanket over her mouth and face with both hands.
After she became motionless, he called his father and a friend for help before dialling the emergency hotline. While waiting for the paramedics, he tried to resuscitate Ms Ny as instructed by the operator but failed. She was pronounced dead at the scene and Lim was arrested the same day.
An autopsy found that she suffocated to death. Bruises were also found all over her body. Toxicology tests found amphetamine and methamphetamine in her system.
Lim also suffered superficial abrasions. A urine test showed he took methamphetamine. His lawyer, Ms Jennifer Lim, urged the court not to impose more than four years for culpable homicide, arguing that his actions were not premeditated.
He was not the aggressor, she argued, citing the corroborative statements of Ms Ny's two friends that she was behaving erratically and he was trying to quell the racket.
The lawyer said the couple had a loving relationship and Ms Ny, who called Lim lao gong, or husband in Mandarin, had proposed to him hours before she died.
She added that Lim's father died from cancer last year while her client was in prison but that her client has an aunt who is willing to take him in after his release.
Deputy Public Prosecutor Lee Zu Zhao sought at least six years for culpable homicide, arguing that Lim cannot say he was provoked as he had a choice not to enter the room to engage Ms Ny.
The maximum punishment for culpable homicide without intention to cause death is 10 years' jail, caning and a fine.