The couple's daughter, who wanted to be known only as Mrs Hong told The New Paper that her mother became depressed after her father revealed his infidelity.
Mrs Hong, 27, and her husband live with her parents in an HDB flat in Jurong East. She requested that her parents not be named.
On Saturday, Mr Tan, 59, was playing "weiqi" (also known as "Go") on the Internet when his wife called out to him.
He saw her seated on the window ledge in the kitchen. He got up and went to his daughter's room to alert her and her husband.
But before they could react, Mrs Tan had fallen to her death from their 11th storey flat.
Now, Mr Tan is resented by his daughter and relatives who blame him for his wife's death.
He confessed to Lianhe Wanbao that he had been having an affair with a woman for the past six years and suggested to his wife that they get a divorce.
He said that although he no longer loved his wife, he still cared for her.
"I thought it would be better if both of us lived our own lives and pursued our own dreams," said the retiree.
"I said I would give her a lump sum maintenance payment and visit her regularly. She accepted it."
Mr Tan said he never thought his suggestion would have a tragic outcome.
He added that while he had many women friends, he has had only one affair.
He declined to reveal more about his mistress, saying only that they met in Singapore.
Mrs Tan is from Penang, Malaysia.
Shin Min Daily News reported that she met Mr Tan after moving to Johor Baru years ago to live with her sisters.
After the couple got married, Mrs Tan worked as a seamstress to support her husband as he was still studying.
After he completed his studies and became an accountant, she continued working to contribute to the household income.
Recalling the events last Saturday, Mrs Hong, an administrative assistant, said her father was playing "weiqi" as usual.
"He spends hours every day on the game," she said.
"At about 5pm, my mother called out to him from the kitchen window."
Mrs Tan had called out "daddy", a nickname she used for her husband.
"He took a look at her, and went to call my husband and me instead, before returning to his game."
That's when Mrs Tan fell to her death.
Mrs Hong, the couple's only child, recalled that the last thing her mother said to her was "eat well" when they spoke at lunch-time.
She added that her mother had been depressed in recent months.
On Friday night, the freelance seamstress had dressed herself in "all white" and told her son-in-law that she wanted to go for a walk.
"It was in the middle of the night. She had never done that before," said Mrs Hong.
Though Mr Tan said he has had "no more love" for his wife in the last 10 years, Mrs Hong said her mother continued to love him.
They were married for 34 years.
She said: "When he was still working as an accountant, she would fetch his shoes and iron his clothes every morning.
"She would sleep on a mattress on the floor so that he could sleep on the bed nearer the fan."
Recently, however, she noticed that her mother had returned to sleeping beside him.
She added that her mother had confided in her best friend about her problems.
Daughter to sever ties with dad
Mrs Hong, who continued to live with her parents after she got married a year ago, said she is waiting for her own flat, due in 2012.
After that, she said, she plans to sever all ties with her father.
When The New Paper visited the family's flat on Monday evening, Mr Tan was bare-bodied and sitting at the dining table, using his computer.
He said that despite his affair, his wife had continued to love him.
"She was a good wife and a good mother," he said.
"Now, the whole world blames me. Nobody wants to listen to my explanation, and nobody wants to accept me.
This is something I have to face."
When contacted yesterday, Mr Tan declined to comment further.
He said in Mandarin: "I don't want to say anything more. I still need to lead my life."
