The grieving Australian woman who watched her fiancé die in front of her in a freak accident at their engagement party is pregnant with their baby.

A family friend identified her as Lilly Watts in an online fundraiser to support her.

Senior Constable Liam Trimmer and Watts were with friends and family when the celebration turned into a tragedy.

He slipped at one point and fell backward. It was unclear what caused the cut to his neck.

Trimmer, 29, died in front of Watts and shocked friends and family.

"Not only has she lost her soulmate, but she also carries the precious gift of new life within her. At almost 14 weeks pregnant, Lilly now faces the prospect of raising a child without her beloved partner, while also grappling with the financial responsibilities that come with homeownership," fundraising organizer Melinda Kelly wrote on GoFundMe.

The money raised was to get counseling and cover the costs of daily living and preparing for the arrival of her baby.

"Lilly's resilience and unwavering spirit have always been her defining qualities, and now, more than ever, she needs our love and support," Kelly wrote.

In an interview with the Daily Mail, Watts said, "I have never known a love like Liam's and this heartbreak and emptiness is just so overwhelming."

"He will always be the love of my life and our baby will know the wonderful man he was," she added.

More than 1,200 people had donated nearly $90,000 AUD in less than 12 hours.

Trimmer moved to Australia about 10 years ago from the UK and graduated from a police academy in 2013.

The Western Australia Police Union said in a statement that it "sends heartfelt condolences to the family, friends, and colleagues of the fallen officer during this difficult period."