Quah Tee Keon's first wife, a Singaporean, was so troubled by the attack in Triang, Malaysia, that she has moved out of her Toa Payoh flat to stay with a friend.
A relative, who answered the door at her flat on Tuesday, said that she had done so to avoid any trouble, Sin Chew Daily reported.
He said that Quah's ex-wife had lost touch with him after their divorce about 11 years ago.
"She is someone who does not look back. They have lost contact after so many years. So he would not come to look for her," he said.
A search on the Registry of Marriages showed that Quah had married her on July 30, 1985.
He married his second wife, Ms Loong Mei Ling, in 2004.
Neighbours of their Woodlands home said they often heard the couple fighting, mostly over money.
A neighbour said: "They often fought, usually before dawn, and this was accompanied by the cries of children. We called the police several times."
The neighbour recalled one occasion when Quah apparently locked his mother-in-law out.
"She was standing outside the metal gate, her cane thrown outside and she was screaming for help."
The neighbours wanted to call the police but Quah shouted at them that he had not done anything wrong.
They described him as a burly man who seldom socialised.
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