36-year-old Woo Mui Mee was convicted of causing grievous hurt after slashing 76-year-old Wong Keng Woo with a paper cutter.
The incident took place at around 10pm at Block 114 Yishun Ring Road on 21 Nov 2015.
Woo, who has been diagnosed with paranoid schizophrenia, was renting a room from Wong at the time.
Angry that Wong switched off the main power supply to the flat unit, she saw him seated a bus stop opposite the block and confronted him, asking him to return.
When he was back at the flat, Wooe scolded him and he threw something on her room door which made her angrier.
She then confronted Mr Wong with the paper cutter and slashed him once on his left forearm outside the flat when she saw him trying to switch on the power supply.
Woo claimed that Wong took a bamboo pole and poked her repeatedly in the abdomen.
She then slashed him again on the forearm before running away.
When SCDF officers arrived, they broke into the unit and found Wong motionless on the bed in the master bedroom.
He was pronounced dead at 11.38pm.
Investigations showed that he died from ischaemic heart disease due to an acute haemorrhage that resulted from an incised wound of the left radial artery.
Woo’s lawyers claimed in mitigation that that her actions were a result of her mental condition, which made her believe Wong was sexually attracted to her.
An Institute of Mental Health report found Woo had no insight into her mental condition, but if given proper treatment before release, her condition could be managed and she would not repeat similar acts in future.