"Losing power can bring forth a pain that hits you like a fist," she wrote in an opinion piece in the Guardian.

The country's first female prime minister was ousted by long-term rival Kevin Rudd amid dismal polling figures.

But despite the switch, Mr Rudd lost last Saturday's general election to conservative leader Tony Abbott.

Labor is set for a new leadership contest after Mr Rudd announced he would resign from his party role.

Ms Gillard revealed she had watched the 7 September election night results on her own.

"I wanted it that way. I wanted to just let myself be swept up in it," she wrote in the Guardian column.

The leadership challenge in June was the second Ms Gillard had faced since taking office in 2010. She herself ousted Mr Rudd as prime minister in 2010.

She said the switch just weeks head of the election had sent Australians a "very cynical and shallow message" about Labor's purpose.

"The decision was not done because caucus now believed Kevin Rudd had the greater talent for governing," she wrote.

"Labor unambiguously sent a very clear message that it cared about nothing other than the prospects of survival of its members of parliament at the polls. There was not one truly original new idea to substitute as the lifeblood of the campaign."

After her own defeat three months ago, Ms Gillard declared she would be leaving politics for good.

"Losing power is felt physically, emotionally, in waves of sensation, in moments of acute distress," she said of that moment.

"You can feel you are fine but then suddenly someone's words of comfort, or finding a memento at the back of the cupboard as you pack up, or even cracking jokes about old times, can bring forth a pain that hits you like a fist, pain so strong you feel it in your guts, your nerve endings."

Ms Gillard said she had experienced "odd moments of relief" since quitting, "as the hard weight that felt like it was sitting uncomfortably between your shoulder blades slips off".

But she admitted that she was still "grieving" the end of her political career.

"Late at night or at quiet moments in the day feelings of regret, memories that make you shine with pride, a sense of being unfulfilled can overwhelm you. Hours slip by."

Mr Abbott and his Liberal-National coalition ended Labor's tumultuous six-year reign in a landslide victory.

During his election campaign, Mr Abbott focused on the rival party's history of political infighting, saying it cared more about personal vendettas than pressing national issues.