Renee Helen Blockey, 43, pleaded guilty to manslaughter in the Brisbane Supreme Court on Tuesday over the killing of John Windle on Macleay Island off southeast Queensland.

The pair argued after getting home-brewed rum from a friend about 10am on April 23, 2018.

Neighbours heard yelling from Blockey's house where the two had returned after drinking for about half an hour.

A postman delivering mail about 12.10pm told police he saw Blockey covered in blood in the doorway, calling frantically for an ambulance as someone was "bleeding out", crown prosecutor Caroline Marco told the court.

Inside the postman saw Mr Windle lying on the floor in a pool of blood. He was moaning while Blockey was crying and holding him.

Asked what happened, she told the postman: "I stabbed him."

Mr Windle died from a 16cm stab wound below his left collar bone.

Officers found a clean, wet hunting knife in the bottom of a shower in the house.

Blockey later told police Mr Windle had angrily accused her of drinking all the home-brew and of being unfaithful. He has also hit her in the face, the court heard.

Ms Marco said the pair had a "volatile" relationship.

She said Blockey told police she owned a hunting knife she called Kitty which she kept in her bedside table because Mr Windle scared her.

But she didn't remember arming herself with the weapon or stabbing him.

Justice John Bond will hand down his decision on a later date.

Australian Associated Press