In 1969, Austrian psychologist Elisabeth Kubler-Ross published her landmark study, On Death and Dying. She concluded people experiencing intense grief go through five stages: denial, anger, bargaining, depression and acceptance. Kubler-Ross’s stages apply in politics too. Just ask Tony Abbott.

Since Malcolm Turnbull struck on 14 September last year, Abbott has been through the wringer. He was deposed by a majority of his own parliamentary colleagues. He lost his prime ministership, his status, his staff and his dignity. He saw long-term friends and supporters betray him, and endured humiliation from the ‘love’ media and political opponents who still despise him.

Proud and decent, Abbott clearly has struggled. He’s found it hard to accept a Prime Minister Turnbull appropriating, without giving credit, his key policies such as stopping the boats, and claiming a Turnbull government is ‘continuity and change’. Amid strident calls for him to quit parliament and public life, Abbott understandably felt driven to vindicate himself and his government, starting with his Margaret Thatcher lecture in London a month after his deposition.

This culminated in two long articles for Quadrant magazine, in which Abbott declared the foreign and domestic policy successes of his government, and a controversial interview from London asserting how he could campaign for the Turnbull government because his successor effectively was standing on a platform of Abbott government policies.

With his interventions, Abbott was seen as disruptive by Turnbull’s supporters and media cheer squad, and some of his grabs are indeed campaign advert gold for Labor’s ad agency. Although Turnbull was allowed to speak his mind amazingly freely when their roles were reversed, Abbott receives no tolerance for doing likewise.

In the process, the ousted PM strayed into dangerous ground for his party and himself: he became an issue undermining the Coalition’s chances of re-election, especially as the Turnbull aura was shown by poll after poll to be fading fast. This lost Abbott some of his key post-coup supporters: conservative columnist Miranda Devine, for one, abandoned him to back Turnbull.

In hindsight, however, Abbott was enduring political and emotional torment most didn’t understand. He was working his way through the Kubler-Ross stages of grief.

Denial in not accepting publicly that his downfall was anything to do with him and his inner circle: rather it was Turnbull, disloyal colleagues and the hostile media. Anger, expressed pointedly but unwisely soon after his ouster in unguarded comments about the role of deputy Julie Bishop and now Treasurer Scott Morrison in smoothing the path for Turnbull. Bargaining, in his plea for six months more after the abortive spill motion in February last year, and in his staying in parliament as an obvious reminder of what was and what could be again. As for depression: Abbott’s a tough and resilient nut but such an emotional trauma endured by him and his family last September and beyond leaves its scars.

Thinking it was done like a Christmas turkey when Turnbull snatched the Liberal leadership, Labor couldn’t believe its luck. It looked that Abbott would be a troubled, disruptive and volatile force in the parliamentary and wider Liberal party, alternatively scorned and pitied by exasperated colleagues as he raged against the dying of his political light.

Until now. The third and final instalment of Abbott’s Quadrant trilogy is published just in time for the start of Turnbull’s double dissolution election campaign. ‘Tony Abbott: I’m not blind to the flaws that ended my leadership’ was how the Australian headlined its edited version of the article, and it’s a fair description.

In this latest piece, reinforced in a subsequent appearance on Sky’s The Bolt Report, Abbott shows public self-awareness missing since the Turnbull putsch. He admits the Abbott government was flawed from the inside, although he takes pains to defend former Treasurer Joe Hockey and his office from sustained criticism received from many quarters. He acknowledges the catastrophic impact of knighting Prince Philip, and how the 2014 budget became a political albratoss around his government’s neck.

Above all, Abbott now acknowledges frankly and honestly how he alienated his own MPs and supporters: over symbolic matters like restricting parliamentary entitlements and privileges; the way he and his inner circle ran the government; and mishandling key policy issues, especially removing Labor’s debt ceiling and failing to honour his pre-election commitment to remove the despised section 18C of the Racial Discrimination Act, a totem issue to his conservative support base that left them wondering what he stood for.

One sentence sums it up. ‘There were always people willing the Abbott government to fail but I made some unnecessary enemies and left too many friends feeling under-appreciated’, he writes. Abbott exudes regret, but a dawning realisation that he was an agent in his own downfall.

Indeed, Abbott has reached the final Kubler-Ross stage: acceptance. The worst of his grieving period is over. Having worked through his grief, Abbott now is ready to re-enter the political fray as a positive and invaluable contributor to the Coalition cause. As he told Andrew Bolt, he wants to be a support and mentor to his colleagues, and a flag-bearer for conservative values.

Not before time. Having frittered away his huge poll advantage with his dilettantism, Turnbull now needs Abbott desperately, campaigning for the government and helping to galvanise Liberal grassroots volunteers unenthusiastic about the now prime minister. Still more importantly, Turnbull needs Abbott to appeal to disillusioned Coalition voters flirting with fringe conservative alternatives to the Liberals because of how Abbott was dispatched. While there are still eight weeks to go until polling day, the Coalition can’t afford to remain divided over the leadership, and an Abbott at peace with himself is an invaluable asset who can help ensure victory over Labor. He can’t be left on the shelf.

Following Abbott’s honourable public mea culpa, Turnbull must show his fallen rival the respect and trust he deserves. Abbott has found his own acceptance: now it’s up to Turnbull to accept him.