Rosemary Gibson, pictured, was murdered by her husband of 44 years - because he wanted to go on holidays

A man who killed his wife in front of their young grandson, shooting her twice in the head as she slept in an armchair, has told a court he did it because she wouldn't go travelling with him.

Alan Charles Gibson, 67, used a .22 calibre rifle to kill Rosemary, his wife of 44 years, at their home in Traralgon, Victoria on April 15, 2016, a court has been told.

Gibson, who has pleaded guilty to his wife's murder, told the court he was 'sorry' his actions hurt his family, the ABC reports.

'I only wanted to go on holidays,' he said.

Mrs Gibson had been caring for her elderly parents before her death.

Alan Gibson, left, pictured alongside his wife, right in happier times, shot her in the head while she slept

She didn't want to travel in their retirement, as they had planned, because she couldn't bear to leave her mother and father unassisted.

This led to Gibson resenting his wife for not spending time with him.

Mrs Gibson had been caring for her elderly parents before her death

Then, after an argument about Gibson cleaning up the house and 'burning the waste, he shot her.

'I just know things were getting to such an extreme turning point it was just, it just, it … but then to come home and after I'd cleaned up, the house looked immaculate and she went right off,' he told police.

Doctor Danny Sullivan assessed Gibson following the murder.

He wrote to the court to say he believed Gibson to be suffering from depression at the time of the attack.

Gibson will be sentenced at a later date.