When Berivan Halo looks back on her wedding day, she does not remember her dress, the festivities or the food.

Key points: Four years ago Berivan Halo's life changed forever when Islamic State (IS) group kidnapped her and her family

Four years ago Berivan Halo's life changed forever when Islamic State (IS) group kidnapped her and her family She eventually escaped after being used as a sex slave for 25 months

She eventually escaped after being used as a sex slave for 25 months Yazidi groups estimate about 3,000 women, girls and children are still unaccounted for

She thinks about how it almost did not happen.

As a member of Iraq's Yazidi ethnic minority and aged 16 at the time, the nuptials were complicated.

Berivan and her fiance Ameen Shakeer Faris had been dating for two years, but needed their families' blessings to tie the knot.

Negotiations lasted a week. Eventually, their happy day was marked with a huge feast.

Four years ago Berivan's life changed forever at the hands of the Islamic State (IS) group when she and her family were kidnapped.

They remained together in captivity for nine months, before the militants separated the men and women.

She has not seen her husband since.

"All I think about is how he is not in my hands anymore, all I can do for him is take care of his kids the best I can," Berivan said.

"There is a really big hole in our lives ... but I'm trying to do my best to be the father and mother at the same time."

Breivan shows off a photo from her wedding day. ( ABC News: Meghna Bali )

Berivan was 24 and pregnant at the time she was abducted.

She eventually escaped, after being used as a sex slave for 25 months — beaten and raped repeatedly along with about 10,000 other Yazidis.

Despite a horrific history of sexual abuse, Berivan counts herself as one of the lucky ones.

IS militants killed her uncle and brother-in-law, and held 22 of her family members in captivity.

The terrorist cell is responsible for a genocide in the Yazidis' ancestral homeland of Sinjar, northern Iraq, in which thousands of women and girls were abducted, sold into slavery and repeatedly abused.

Some were advertised like commodities on encrypted messaging apps.

In the last six months of her ordeal, Berivan was separated from two of her four young children, a boy and a girl, who would be sold in IS slave markets.

"Everything changed since that moment," she said.

"Our lives since then is just sadness and crying."

Many Yazidi towns remain uninhabitable due to bombs and explosive traps left by retreating IS fighters. ( ABC News: Tracey Shelton )

Casualty estimates vary, however, the United Nations believe the "400,000-strong community had all been displaced, captured or killed".

Berivan and her children survived, and, since May, have been living in Coffs Harbour on the New South Wales mid-north coast.

Despite freedom from the physical horrors of IS, she said she was worried about those still missing, particularly the women.

"One girl may be raped 10 times a day by different men, I've been going through all of that, there was nothing they didn't do to us," she said.

"It doesn't matter that we be killed or captured or we be in jail or we be tortured, the hardest thing for Yazidi ladies has been to be sold as sexual slaves."

The Yazidis' homeland borders Syria, and their centuries-old faith combines aspects of Islam, Christianity and Judaism, among other religions.

The minority has been dubbed "devil worshippers" and polytheists by IS militants.

Thousands still unaccounted for

Berivan is defiant, but frustrated.

"It's really fine for me to talk about everything, all we want is to get our voice to the other people, to the other parts of the world," she said.

But sometimes she feels like no-one is listening.

At the end of last year, Yazidi groups estimated about 3,000 women, girls and children were still unaccounted for.

Berivan's openness to share her harrowing past is a trait shared by Yazidi men and women who have resettled across Australia.

"If we were not very strong and if we were not powerful people, we won't survive like that, we wouldn't be standing right now with this energy and strength," Berivan said.

Berivan and her children are starting a new life on the NSW mid-north coast. ( ABC News: Meghna Bali )

Coffs Harbour now has more than 80 Yazidi families living in its community, most of whom have arrived in the past 15 months.

This week, the community will gather in the Coffs Harbour Girl Guides Hall to mark the fourth anniversary of the massacre.

Many of them have heartbreaking stories.

During August 2014, tens of thousands of Yazidis escaped to Mount Sinjar, where IS surrounded them.

Australian forces joined the US, Iraq, Britain and France in flying in supplies, until US-backed Kurdish fighters eventually opened a corridor to allow them to safety.

They were the lucky ones.

Yazidi boys were forced to fight with the extremists, or executed with the men. At least 54 mass graves have been found in the Sinjar area.

'I will never give up'

Despite the grief of leaving much of her family behind, Berivan said resettling in Australia was the right decision for the sake of her children.

"I think they're in a process of healing," she said.

"Even though they had a lot of sadness and hard times, I'm hoping that will convert to happiness in their future and that makes me a little bit happier."

Berivan is learning English, and said she felt supported by local services.

"Right now I have nothing to offer to them, all what I have is my respect for them and I don't think at any time I will be able to pay back what they've done for us," she said.

"I'm hoping one day I become an active person in this community and this country, to pay back at least a little bit of what they've done for us."

But right now, her focus is on the Yazidi community, and the looming anniversary.

There will be separate rooms for the adults and children, where families will bring photographs of their loved ones, light candles and share stories.

"You can sit up with us and you spend hours and hours talking, it never ends because of what we've been through," Berivan said.

Berivan will take pictures of her seven captured family members, including her husband.

"Till the last moment of my life I will never give up hope that I will see them," she said.

"I don't know anything, I never heard anything about them, but I won't give up."