As the protests in Turkey continue, spare a thought for the man whose personal tragedy few have the grace to acknowledge – Recep Tayyip Erdoğan. Until three weeks ago Erdoğan was destined to go down as one of the greatest reformers in Turkish history alongside Ataturk and Suleiman the Magnificent, despite all the bullying and the backsliding of the past three years.

Here was a man who seemed to have the power to tackle Turkey's century of conflict with the Kurds, Armenians and Greeks, and to lead it to a peaceful, prosperous, and democratic future – a model not just for Muslim countries but for other rising economic powers shaking off less than perfect pasts.

But Erdoğan's greatest achievement – greater still than a decade-long boom that bucked global depression – was his breaking of the power of the military that had shackled Turkish democracy for so long. In pre-Erdoğan Turkey, we would have had a coup by now.

Yet the power he concentrated to defeat the generals – by foul means as well as fair – and the paranoia of that battle, has undone him. In a matter of days Erdoğan has become the personification of all the corrupt despotism and violence of the old Kemalist Turkey he was elected to sweep away.

The ironic thing is that he has done this to himself. Such was his grip on power that only Erdoğan could have destroyed Erdoğan. And that is what he has done by turning an insignificant protest in a scrubby little park into a national emergency.

I met Erdoğan twice while he was mayor of Istanbul – and there was much I liked about him. No other European leader has risen from humbler beginnings – nor had so much stacked against them.

He had the warmth and emotion of his Georgian roots, and then at least, an uncommon sincerity. He had a clear vision – to make Istanbul work and right historic wrongs he believed religious Anatolian conservatives had suffered at the hands of Turkey's secular elite. Behind this was a hazy notion of rolling back time to an Ottoman nirvana of what might have been if Ataturk and the Young Turks – neither much troubled with democracy – had not existed.

What struck me then was how Erdoğan's telling of his own story unconsciously mirrored Ataturk's – and the lingering suspicion that he too believed Turks needed to be told what was good for them.

With Erdoğan's power having become so personalised, and self-censorship so rife that a press baron openly consulted him last month as to who should edit one of his papers, it was clear Erdoğan had vanquished the generals only to adopt their methods. His response to the Gezi crisis came straight from the old Kemalist coup handbook: brutality, black propaganda, conspiracy theories and lots of bad faith. Few politicians get into people's heads the way Erdoğan does. His hectoring manner and his way of tying logic in knots may play well with his supporters but it drives many more Turks mad.

Just as Erdoğan became all-powerful he also became personally vulnerable, battling cancer and grieving the loss of his mother who had shielded him from his frustrated and over-religious father – whose worst traits his son is now displaying as he tours Turkey to chastise his ungrateful children at a series of monster rallies: "Look what I have done for them! And this is how they reward me?" The "pious generations" he had talked of raising have spoken back.

Islamist hubris alone has not undone Erdoğan; it's more the mile-wide authoritarian streak he inherited from Ataturk and which runs through Turkish life, filtering down to humblest officials currying favour by second guessing and zealously enforcing their superiors' orders.

What we are witnessing here is pure Shakespearean tragedy but one that threatens to turn into a national calamity. That Erdoğan called his "people" together on Sunday in Istanbul at the place where Mehmet the Conqueror gathered his troops for the assault on the old Byzantine capital, added another layer of foreboding.

Turkey is in a dark place but Gezi may yet prove to be a turning point on the twisted path to democracy. One thing is for sure, the broad coalition that brought the AK party to power has been broken, perhaps forever.

Over the weekend I talked to a textile magnate from Kayseri, one of the many "Anatolian tigers" whose money has bankrolled Erdoğan's party. He was sending his workers on free buses to the first of Erdoğan's monster rallies but his headscarfed daughter was no longer talking to him over his support for him. "There are arguments in the house every day."

When I asked if he still backed Erdoğan's campaign to change the constitution so he could become a French or Russian-style president, his tone changed: "We cannot make this man president. Not now. Tayyip may destroy us all yet."