He had just woken up at 8.30am on Sunday and saw his wife next to him in bed.
She had been battling a bout of flu for the past few days, but not wanting to wake her, he decided to take her temperature with a thermometer.
It was low, but Mr Raymond Tan, 36, thought it could be due to the air-conditioning. Then he noticed his wife's jaw, which looked crooked and stiff.
Realising that something was wrong, he panicked, and started performing cardiopulmonary resuscitation (CPR) on her.
It was too late - Mrs Dion Tan, 36, had already been dead for the past two to three hours, said paramedics who arrived at the scene later.
It all started last Thursday, when Mrs Tan came down with fever of about 39 deg C.
After work, she visited a clinic in Chong Pang with her husband, who assumed that the illness was something she would recover from within days.
Mrs Tan, a quantity surveyor with an interior design firm, had always been healthy and had no history of medical problems, he explained.
She was prescribed medication for fever, cough and a course of antibiotics, he said.
When Mrs Tan did not get better, the couple visited another clinic, in Marsiling, on Saturday evening,
"The doctor said maybe it was a viral infection, but did not seem too alarmed nor was she advised to visit the hospital," said the construction site manager in Mandarin.
After taking the medication she was prescribed, MrsTan went to bed at about 10pm . That was the last time he saw her alive.
"When I was performing CPR and calling out 'Baby! Baby!', some part of me already knew that there would be no use. But I was really still hoping for a miracle," said Mr Tan at his wife's wake on Monday.
Guilt set in shortly after.
"I took some cough syrup which made me drowsy before going to sleep, so I wondered if I slept through her cries for help or something," he said.
As of now, he still has no clue what caused his wife to die so suddenly.
A report, which will reveal her cause of death, will only be ready in a few months' time.
The couple have two children, one aged four years old and the other four months old.
They met in 1996 while they were studying in Kuala Lumpur. Mr and Mrs Tan, who are from Malacca and Muar in Malaysia respectively, tied the knot in Singapore in 2004 .
Mr Tan is now Singaporean, and his wife was a permanent resident.
Mrs Tan, who had seven siblings, loved large, boisterous family gatherings and had a soft spot for kids.
Said her elder sister, Madam Kennis Sik: "Before she had her own kids, she would treat our kids (her nieces and nephews) as her own.
"She loved taking pictures with them, and the kids loved her too. She was so good-natured and kind.
Her death is something the whole family cannot accept." After her sister's death, Madam Sik volunteered to care for the couple's four-year-old daughter, Chermaine.
Madam Sik's mother offered to take care of Ryan, the four-month-old son.
These are suggestions Mr Tan is deeply grateful for, but he is reluctant to accept.
He said: "When we decided to have our second child, it was because we did not want our first to be lonely.
"We wanted her to have a companion. So I would like them to be together," said Mr Tan, who lived with his wife in a five-room HDB flat.
Still reeling from his wife's sudden death, Mr Tan revealed: "A couple of years ago, she casually mentioned that out of the two of us, she hoped to die first, so that she would not have to cope with the grief.
"I never knew it would be so soon."
Speaking fondly of his wife, whom he called "baby" and "bao bei" (darling in Mandarin), he said: "She was not the kind of wife who wanted to manage her own pay cheque as well as her husband's.
"The money we earned was ours. We settled problems we had together."
Mr Tan said they had plans for a weekend getaway, which will never be realised now.
"We planned to visit a golf resort in Skudai, Johor Baru, this coming Saturday. It has been about four years since we played golf because we were busy with the babies.
"We even bought swimwear for our children and floats for them to go swimming.
"Now we won't be able to use them," he said.
"When I was performing CPR and calling out 'Baby! Baby!', some part of me already knew that there would be no use. But I was really still hoping for a miracle." - Mr Raymond Tan
This article was first published in The New Paper.