Emmanuelle Sinclair, who hosted the party, described the occasion as a chance for the group to socialise and have a few drinks.
"[It was] supposed to be a good day - everyone was looking forward to it," she told the court.
However, she said Browne later became "aggressive, irritated" with other people at the party.
"She was saying rude things, saying she was a 'gang whore'.
"We had a fight, we had a real tussle, the drawers were pushed over straight into the bedroom wall.
"She just got real angry," Sinclair said of Browne.
The court heard how Stewart later said to Browne, "how dare you do this, this is a family home".
"At some point me and Carly had said between us 'what was she on?'" Sinclair told the court, but added "there was definitely no drugs there".
A fluid fight between Browne and Stewart then began, Sinclair said.
"Anna hit Carly, both had a hold of each other, hitting each other ... they were tussling."
Browne and Stewart were pulled apart before Stewart said, "yep, I'll be the bigger person'".
"She said she wasn't scared ... scared of Anna," Sinclair added.
However, moments later Sinclair entered the lounge to find Stewart had been stabbed.
She described the desperate attempt to save her friend's life by applying pressure to the knife wound in her head.
Earlier the court heard how an 11cm deep knife wound, cutting a major vein in the left side of Stewart's face led to heart failure and her lungs filling with blood.
The court was also shown a graphic 360-degree photographed view of the crime scene, taken just hours after the stabbing.
Inside the home's blood-splattered lounge, near the doorway to the kitchen, lay Stewart's lifeless body. First aid kits could also be seen strewn about the room.
As the 360-degree view moved into the kitchen, a bloodied butcher's knife could be seen sitting in the sink next to a steel pot, a pink plastic bowl and some cutlery.
Justice Edwin Wylie warned the jury about the graphic nature of the photos, which were used to aid pathologist Dr Thambirajah Balachandra's evidence.
Balachandra said he noticed evidence of resuscitation with marks from two defibrillator pads but more striking was a major stab wound to the left side of her face.
He said a vein in Stewart's neck had been severed when the knife entered the left side of her face, deep enough to hit the right side of her throat.
He estimated the wound to be about 11cm deep.
About 150ml of blood was also found in Stewart's stomach as well as blood in her airways.
He told the court that as Stewart was "trying harder to breathe air was sucked into the open vein".
This led to air in the right side of her heart, which "compromises the working of the heart", he said.
Balachandra concluded that a massive loss of blood, blood in the airways, and air bubbles in the heart were a direct consequence of the stabbing.
He said there was also alcohol in Stewart's blood and urine, and several bruises were found on her limbs.
Opening the Crown case yesterday, prosecutor Nick Webby said Browne was friends with Stewart, but had become increasingly aggressive during the party.
After entering the kitchen of the West Auckland home, Browne "picked up the biggest knife in the butcher's block" before attacking Stewart, the Crown said.
Stewart was left holding a towel against the side of her neck in the moments after the attack, according to recordings of 111 emergency calls played to the court.
Stewart's cousin Patricia Stewart told a St John paramedic that despite the towel being pressed against the wound, blood was "everywhere" and running out her cousin's mouth and nose.
Constable Corina Willey also told the court this morning, through a read statement, that she arrived to find "blood all over the carpet, [and Stewart's] face was covered in blood".
She said she was shown a bloody knife in the kitchen sink, which she estimated was about 30cm long, with a 20cm blade.
