While he was asleep, Prasad took his cellphone out of his pocket and started rifling through his texts.
She found messages to a woman she did not know and phoned to confront her.
The mystery woman did not answer, and so Prasad turned her attention to Mr Burton and furiously picked up a 30cm knife.
Christchurch District Court heard that just after midnight Prasad then threw the knife at him, which struck him in the head, and lodged in his skull.
Prasad phoned an ambulance and Mr Burton was taken to hospital where the knife was removed. He was discharged later that morning.
When asked by police what happened, Prasad admitted "being angry" when she threw it.
Prasad today pleaded guilty to an amended charge that she caused grievous bodily harm to Mr Burton with reckless disregard for the safety of others.
Defence counsel Serena Bailey said the pair began a relationship early last year and that at the time Prasad was pregnant with their child.
She gave birth to the baby last week, and Ms Bailey said Prasad was "very keen" to put the incident behind her.
While the couple are not back in the same house, they are back together and jointly caring for their child.
Interim name suppression was not continued today, and Judge John Strettell remanded Prasad on continued bail until sentencing on October 29.