"It was a beautiful day, we are all sisters that grew up together. An outsider came in, no one knew that was going to happen."
She said the accused was only at the gathering for 20 minutes.
"We are all just devastated, just really wrecked. We just want her back, but we don't even have her back yet."
Her home, which is rented from the property owners, was still cordoned off by police yesterday but she was able to briefly return to get some belongings for her family.
She said the victim's children were not present, but her own and others were.
A neighbour said he walked past the gathering at about 10am and it seemed "lovely".
"There were children playing and laughing, lots of cars parked outside."
When he returned home at about 4pm, it had descended into chaos, he said.
"There were police cars everywhere, a poor little child was sobbing his eyes out in the street."
On Saturday night, family members waited outside the cordon until they were let inside to perform a guard of honour and perform a haka as the body was loaded into a hearse.
Police said a post-mortem on the dead woman took place yesterday. The stabbing came just hours before another stabbing about 5km away in Glendene, where a man also died of his injuries.