A court in Australia on Monday sentenced an Indian-origin woman to 18 years in jail for the murder of her ex-lover's fiance out of jealousy and rage, a media report said.

New South Wales Supreme Court Justice Helen Wilson handed down the sentence to Manisha Patel, 32, after finding that she intended to kill the victim who became the focus of her "pain and resentment", the Herald Sun reported.

Purvi Joshi, who had moved to Sydney from India to get married in November 2013, was found dead by her fiance Niraj Dave in his apartment in Sydney's Kyeemagh on July 30, 2013. A knife was found sticking out of Joshi's abdomen.

In July this year, Patel was found guilty of murdering Joshi.

Patel said she went to the apartment that morning while Dave was working because Joshi had demanded to know about their past relationship. Once there, she said she killed Joshi in self-defence.

However, handing down the sentence on Monday, Justice Wilson said: "At some point, she (Patel) must have known she (Joshi) was fighting for her life."

The court heard that Patel met Dave on the Indian matrimonial website shaadi.com in August 2011.

They became friends, moved in together and began a sexual relationship.

In early 2012, after formally ending his marriage with his wife in India, Dave began talking to Joshi to who he said Patel was "just a friend".

In March 2013, Patel became pregnant following a drunken weekend with Dave and they organised to have a termination.

But just before Joshi arrived in Australia, Dave asked Patel to leave his flat and hand over the keys to a car they had bought together.

This, Justice Wilson said, "must have crystallised the offender's dramatic change in her own circumstances".

Joshi, meanwhile, was completely innocent and had no idea she had walked into a "psychodrama not of her own making", the judge said.