News that Boris Johnson’s wife Marina has finally left him provided social media with some light relief from the ongoing tragedy of Brexit.

“Leave means Leave ... £350 million divorce settlement ... he’s screwed the whole country.”

Mind you, I don’t think many of Boris’s admirers rate him for his adherence to family values, and anyway 40 per cent of marriages these days end in divorce. What’s much more serious than Johnson’s marital infidelities was the suggestion, circulated last week, that he privately regrets having plunged the country into the chaos of Brexit.

A degree of contrition here would be welcome from the politician who said that Brexit would “let the British lion roar”.

Surely, not even the hardest of Brexit Tories can be exactly proud of what has happened over the last two years.

We’ve gone from roaring beasts to Operation Yellowhammer, the government’s emergency planning for what sounds like an imminent economic and social catastrophe. The Civil Contingencies Secretariat, which drew up last week’s leaked papers, normally deals with events like the Grenfell fire.

Not only did the documents warn of increased costs of managing the crisis, they appeared to raise questions about aviation and rail travel to Europe if there is no deal with Brussels this winter.

Brexiters smelled a rat: there’s suspicion that the “appeasers”, as Remain supporting Cabinet ministers are called, had connived at the exposure to the cameras of the Yellowhammer documents by the Treasury Minister John Glen. Part of a campaign to spread fear and alarm. Well, they hardly need to do much spreading.

Glen’s boss, Chancellor Philip Hammond, has done more to alert Britain to the growing costs and penalties of Brexit than Jeremy Corbyn. Last week, Hammond cancelled a tax cut to millions of self-employed workers and warned about further Brexit-related tax hikes. On a visit to Scotland, he told The Herald that we could expect further spending cuts.

Last month, he wrote that a failure to secure a trade deal with Brussels could increase borrowing by £80 billion and wipe 15 per cent off GDP over the next 15 years.

You’d think no sane government would actively plan for such an outcome, but as we know, the UK Government is doing precisely that. Foreign Secretary Dominic Raab and Theresa May have repeatedly said that “No Deal is better than a bad deal”, possibly the most irresponsible economic soundbite uttered by a British government in peacetime.

It’s like saying a repeat of the 2008 financial crisis is a price worth paying for saving the government’s face.

Truth is, there’s no deal that’s worse than No Deal. It would destroy Britain’s relations with our largest trading partner, destabilise Northern Ireland, force car manufacturers to leave, strand thousands of expatriate Britons in the EU, produce chaos at the ports, leave a legacy of bitterness and conflict of which the scallop wars are a dire portent.

It would ruin hopes of retaining the benefits of EU citizenship: the freedom to move and seek work in Europe, the protections against workplace exploitation, the environmental standards we take for granted.

Everyone knows this, even Theresa May, but no-one seems able to halt the runaway Brexit express as it heads for the buffers.

The Opposition is almost as culpable here. Labour has failed to provide any coherent alternative to hard Brexit. Corbyn has rejected Theresa May’s bankrupt Chequers plan for partially remaining in the Customs Union, but has offered nothing in its place. He’s ruled out the Customs Union, the Norway option, and has even rejected a People’s Vote to halt the runaway train. This has little to do with hostility to the EU (Corbyn actually voted Remain) and a lot to do with narrow-minded political self-interest.

Labour clearly hopes that by keeping its head below the parapet it will haste the Tories’ self-destruction, and precipitate a general election. This is not just irresponsible, it is foolish politics. If Labour were elected just after Britain hits the Brexit buffers, it is Jeremy Corbyn’s government that will be blamed for the ensuing chaos.

Tories like Jacob Rees-Mogg are content to sit back for five years until the Tories are re-elected by angry voters.

Brexiters are playing a long game. Theresa May is playing a very short game indeed: relying on reckless brinkmanship. The UK appears to be refusing to negotiate over the Irish border in the hope that Brussels is forced to make concessions in order to avoid destabilising the province.

In December, the UK agreed that, as a back-stop, Northern Ireland should remain in “regulatory alignment” with the single market in order to shore up the Good Friday Agreement. However, the UK has neglected to make any concrete proposals for how this can be achieved.

Instead, the Prime Minister has reassured her coalition partners, the DUP, that there can be “no border in the Irish Sea”, and has placed an amendment to the UK Customs Bill, making any such thing illegal. The move is presumably intended to force the EU negotiator, Michel Barnier, to allow the entire UK to remain in regulatory alignment as the only way of squaring the Irish circle.

Friction-free access to the single market with no freedom of movement or Brussels rules. Job done.

Except there is very little likelihood that the 27 states of the EU will agree to this, since it would wreck the EU.

The only solution Brussels can offer is membership of the European Economic Area, like Norway, which means accepting the single market’s rules while remaining outside the EU. Meanwhile, the situation in Northern Ireland deteriorates by the week – it is now 600 days since it had a government.

There are moves in the North, not just among Irish nationalists, toward reunification of Ireland – a move which the DUP will never accept. The No Dealers are warning of the break up Britain – actually they may be right about that, but it won’t be the fault of Brussels.

Hard Brexiters seem to think that we can leave the EU without there being any erection of borders or dislocation of trade. It’s magical thinking. They think we would immediately get a Canada-style free trade deal, or at least automatic adoption of the World Trade Organisation tariffs.

But the Canada deal took seven years to negotiate, and doesn’t cover services, 80 per cent of the UK economy. Even WTO schedules, the trading rules, have to be negotiated.

And, even if these could be applied instantly, there would still be dislocation under No Deal because our relations with the EU involve so much more than just trade tariffs.

There are all the regulatory standards that have to be observed. Britain has common arrangements with Europe on everything from the safety of medicines to the freedom to fly.

Playing the No Deal card is not good negotiating tactics. It’s the brain-dead economic nationalism of Donald Trump – a politician whose “robust” negotiating style has been commended by Boris Johnson. The former Foreign Secretary likes to think of himself as a Churchillian figure, a national saviour.

History will judge Johnson as a kind of moral delinquent, a political arsonist, who has unleashed a conflagration that will consume him, his party and his country’s prosperity.