Four days before Christmas, a drunk-driver killed Dimity's sister and brother-in-law.

This time of year is tainted by grief for Channel 9 reporter Dimity Clancey.

Nineteen years ago, just four days before Christmas and just three weeks after their wedding, her sister and brother-in-law were killed by a drunk driver; a man who chose to get behind the wheel despite being four times over the legal limit.

Clancey was just 14 when police knocked on the door to break the tragic news to her parents.

“I heard the words ‘killed’ and ‘Dominique and Andrew’ and then I heard my mum just scream,” Clancey told The Daily Telegraph.

The couple, both doctors, died instantly when Tuipulodu Mahe, an illegal immigrant from Tonga, crossed onto the wrong side of the M4 motorway in Sydney and slammed head-on in to their hatchback.

Dominique, 27, and Andrew, 26, had been on their way home from visiting friends, after earlier celebrating Christmas with the Clancey family at Carols in the Domain.

That day, December 21 in 1997, was the day the journalist says her whole world changed.

“My sister had her dreams stolen and hundreds of people were robbed of her love and care as a doctor,” Clancey said.  “Andrew’s too.”

Now 33 and a mother to a 16-month-old son, Clancey wrote on Instagram that while her husband and child help her through the grief at this time of year, she still misses her so deeply that she cries herself to sleep.

"I think about her every single day and wonder about all the lives she would have saved," she wrote.

As a parent, she thinks about her own mother and father, how the tragedy "fractured" her family.

“It’s hard enough losing a sister but I just can’t ­imagine the pain of losing your child,” Clancey told The Daily Telegraph.

Mahe, who lost his brother and seriously injured himself and his daughter in the crash, spent four years behind bars for his crime, before ultimately being deported.

While she normally doesn't speak about what happened, Clancey said she hopes her decision to share her family's story will help others to learn from it and think twice before drink driving this Christmas.

“Every decision you make has a consequence, whether good or bad,” she told The Telegraph.

“If it saves one life, then it’s worth it.”