A fashion designer siphoned off $80,000 from his former lover's online bank account, claiming he was left "hurt" and "upset" when their 17-year relationship ended.
Ong Teck Hock was caught in bed with another man by his teacher partner in 2011 and moved out of their home.
He then began transferring the teacher's cash to his account.
Ong, 40, was jailed for five months yesterday after he pleaded guilty to seven charges under the Computer Misuse Act. He admitted to 15 similar charges, which were considered in sentencing.
The Malaysian got into a relationship with the teacher in 1995. The latter took care of Ong's expenses and gave him a monthly allowance. He even paid for Ong's diploma in fashion design.
In 2010, Ong suggested that the teacher apply for online banking facilities. As his partner was not proficient in using computers, Ong kept his Internet banking token.
In November 2011, Ong's friend visited him at home and the two fell asleep on the same bed. When the teacher came home and saw them, Ong was unable to explain himself fully. He moved out about two weeks later.
Ong later heard from mutual friends that his former partner was spreading rumours, saying he had stayed with him only for his money, the court heard. He also heard the teacher had found another lover.
Ong started transferring funds from the teacher's bank account to his own. Between September 2012 and June 2014, he transferred $82,853 in all. On July 18, 2014, the teacher, now 62, told police that someone had made unauthorised transfers from his bank account and a cheque he had issued bounced due to a lack of funds.
Ong, a permanent resident, could have been jailed for three years and fined $10,000 on each charge.