Like sheep, the British people, regardless of whether they support Brexit, are being herded off a cliff, duped and misled by the most irresponsible, least trustworthy government in living memory. The moment when article 50 is triggered, signalling Britain’s irreversible decision to quit the EU, approaches inexorably. This week, on Black Wednesday, the UK will throw into jeopardy the achievements of 60 years of unparalleled European peace, security and prosperity from which it has greatly benefited. And for what?

The ultra-hard Tory Brexit break with Europe that is now seen as the most likely outcome when the two-year negotiation concludes is the peacetime equivalent of the ignominious retreat from Dunkirk. It is a national catastrophe by any measure. It is a historic error. And Theresa May, figuratively waving the cross of St George atop the white cliffs of Dover like a tone-deaf parody of Vera Lynn, will be remembered as the principal author of the debacle. This is not liberation, as Ukip argues, nor even a fresh start. It is a reckless, foolhardy leap into the unknown and the prelude, perhaps, to what the existentialist writer Albert Camus described in La chute – a fall from grace, in every conceivable sense.

It did not have to be this way. Like others who favoured Remain, we have reiterated, ad nauseam, our acceptance of the referendum result. But whether you were for or against, what confronts us all now is drastically different from what was on the table last June. The hard Tory Brexit in prospect represents an epic act of self-harm. A more enlightened Conservative prime minister, better attuned to the “one nation” tradition of the party of Disraeli and Macmillan, less in thrall to Little Englanders, and less intimidated by the peculiarly vicious and Manichaean worldview of the Daily Mail, would have taken a more consensual approach. Yet despite her promises when she became prime minister, Theresa May has failed to heal the divisions caused by Brexit.

Far from reuniting a fractured kingdom, she has divided it further, perhaps fatally, as the SNP’s unsettling decision last week to push for a second Scottish independence referendum implies. As Lord Heseltine has suggested, a more imaginative, braver and more consistent leader could have used the referendum result to propel an immediate negotiation with the EU on much-needed reforms. If, at the end of that process, Britain’s demands remained unmet, the divorce could have proceeded or, if a deal were agreed, been put to a second vote. Instead, May, more sheep than shepherd, has feebly allowed herself to be driven ever further towards an extreme, inflexible, take-it-or-leave-it stance for which she has neither mandate nor credible grounds.

The main reason that May and her ministers now say that no deal would be better than a bad deal is that even the most blinkered Brexiters have belatedly realised what an impossible position they have placed the country in. They simply cannot deliver what they promised. Nor will an affronted, alienated Brussels help them do so. Rejigged single market access? Forget it. A bespoke customs union? Not a chance. A free trade deal within two years? In your dreams. It has become crystal clear that none of this is possible while ministers continue to reject freedom of movement and other basic EU principles, including European court of justice jurisdiction. On this, the other 27 countries are united. So now the hard Brexiters say, with astonishingly cynical mendacity, that Britain would be better off going it alone. This approach plays fast and loose with ordinary people’s livelihoods. Yet still, with jingoistic horns and trumpets drowning out the roar of the deep, the stampede towards the cliff’s edge gathers pace.

Every day produces more evidence that this hard Tory Brexit is a disaster in the making. Carmakers and other export manufacturers, fearing swingeing tariffs, are demanding special protections and exemptions or else they leave. Professional bodies, ranging from lawyers to economists, warn of endlessly damaging business consequences. The NHS faces the loss of tens of thousands of qualified doctors and nurses it has no prospect of replacing. Care homes are in a similar plight. Banks, financial institutions and airlines face unavoidable decisions about moving jobs and operations to mainland Europe.

Environmentalists rightly fear the cleaner rivers and cleaner air ensured by EU regulations (red tape to the Europhobes) may soon become a thing of the past. British citizens living and working in Europe fear the chaos that would surely follow all-out rupture; likewise EU citizens living here. Britain’s farmers, like its academics, surely realise by now, if they did not before, that they cannot trust this government to replicate the research funding, subsidies and employment freedoms that EU membership currently bestows. The average British family is now hemmed in by multiple, authoritative predictions of stagnant or falling wages, higher food and fuel prices, an ongoing sterling devaluation, collapsing social care and public services and increased, regressive indirect taxation. Be you a Remainer or a Leaver, you would have to be particularly obtuse not to see that May’s hard Tory Brexit will cost this country and its families more than it can conceivably afford.

The prospective political, diplomatic and reputational cost is every bit as daunting. Take the damage to Britain’s democracy. Last week, parliament was at its best, uniting in defiance of terrorism. The week before, it was at its worst, agreeing to deny itself a meaningful vote on any final deal. The government argued that to do otherwise would tie its hands. This is baloney. David Davis, Liam Fox, Boris Johnson and the other Brexit blowhards know they have no chance of achieving their stated aims, such as a £350m weekly NHS payback. So they pre-emptively reject parliamentary scrutiny, dismiss any criticism as unpatriotic and hope, like the cheap chancers they are, that they will get away with it. They’ve peddled a fake Brexit, full of false promises. The reality is beginning to dawn.

Unconscionably, they and their outliers in the hard Brexit media have attempted to stifle debate and question those who demand proper scrutiny of the most significant political and economic challenge to Britain in decades. They have helped foster a corrosive, mean-spirited, angry and divisive atmosphere that May and her lieutenants are too weak to challenge. Into this swill comes Leave financier-in-chief, Arron Banks, who last week announced he was setting up a “Patriotic Alliance” to attempt to unseat 100 Remain-supporting MPs. The Daily Mail, Katie Hopkins, Arron Banks, Nigel Farage, Paul Nuttall – meet Britain’s new patriots. Except they’re not, because divisiveness and intolerance are not the values of patriots.

There is a criticism of one’s country that is born of hate and a criticism born of love. And they are materially different. One wishes to divide us, the other attempts to bind, cohere and support. It fell last week to Michel Barnier, the EU’s chief negotiator, to throw a cold bucket of reality over the ultra-hard Brexiters’ fantasies. The effect was chilling. Barnier made clear May’s “no deal” option was no option at all. He warned of queues of lorries at Dover, chaos for ordinary citizens and custom controls on trade from day one of the UK’s withdrawal. Barnier also made plain the EU would not even begin to talk about a post-Brexit trade deal until Britain agrees to cough up the estimated £50bn Brussels says it owes in prior commitments. The figure is disputed. But the principle is not. Britain faces a hugely costly settling of accounts, whatever parti pris barristers may advise. For good measure, Barnier insisted the Irish border conundrum and citizens’ rights must be resolved before other Brexit matters can be discussed.

Barnier says the EU wants a deal. And it would be reckless indeed for EU leaders to ignore the factors that produced the Brexit vote, many of which can be observed across the union. The EU itself is becoming uncomfortably aware that as well as a need to show flexibility towards the UK, it also has to demonstrate to its own citizens an awareness of its democratic and policy deficiencies if it is to rekindle the support that has seen it develop since its origins in the Treaty of Rome 60 years ago.

But Barnier’s stance, if unchanged, presages a negotiations humiliation for the government. Yet more threatening for the ultra-hard Brexit brigade and the lie factories of Fleet Street was Barnier’s vow to spell out what leaving the EU really entails for the British people. “We need to tell the truth and we will tell the truth to our citizens about what Brexit means,” Barnier said, his point being that, until now, here and elsewhere, such truths have been deliberately concealed, ignored or distorted. How galling, and how ironic, that the country, the “mother of parliaments” that boastfully styles itself the home of modern representative governance, should need a lesson in open democracy. But needed it is. Truth and common sense are in short supply as Britain charges towards the precipice.