The Palace of Westminster lends itself well to hide-and-seek. The Gothic labyrinth of interconnecting passageways and stairwells defies navigation. It contains a million places of concealment. But there are times when the division bell rings, and MPs must show themselves. The game ends and everyone sees who stands where. The vote on Theresa May’s Brexit deal should be such a moment of revelation.

It is two years since parliament voted to propel the UK out of the European Union, giving May authorisation to pull the article 50 trigger. Then the great game of hide-and-seek began. A small minority of MPs dared to declare Brexit a bad business from the start. They saw how reckless it was to set off on the journey without a map or a notion of the destination. But most hid, not in niches behind stone pillars but in bogus arguments and behind plastic loyalties.

For many Tory Brexiteers this has really been a continuation of a game that started when David Cameron first promised an EU referendum in 2013. Few then admitted that total rupture from the EU was their only acceptable outcome. They made common cause with Nigel Farage but hid behind talk of “repatriating powers”. They tucked themselves in behind Cameron’s “renegotiation”, pretending that the right concession might satisfy their obviously insatiable appetites. Once the referendum campaign was under way, they hid in Boris Johnson’s bluster-bus. They pretended that Brexit would be simple; that money would flow for the NHS. They shrouded their ignorance of EU institutions and inexperience in trade negotiations in layers of bombast and lies.

Some then hid in May’s cabinet, behind her red lines, until the true balance of power between the UK and the EU became clear. Johnson, David Davis, Esther McVey, Dominic Raab – they all fled the cabinet and took cover elsewhere. A popular hiding place is behind the flimsy screen marked “WTO rules”. That bare-bones apparatus doesn’t begin to insulate a developed economy from the shock of ripping up economic ties that have evolved over a generation. The Brexit ultras conceal their excitement at such a shock.

It isn’t just backbenchers playing this game. There are Eurosceptic ministers who endorse May’s deal, but only because they see in its vagueness the opportunity for a more radical split from Europe down the line. Then there are pro-Europeans, including cabinet ministers, who intend to vote for the deal while hoping that others will bring it down. They feel they must publicly demonstrate loyalty to May’s Brexit before trying to steer her in a different and much softer direction.

Meanwhile, Labour tries in vain to hide its Brexit confusion with demands for a general election. If that wish is granted, the opposition would still stand paralysed at the same junction, facing the same roads leading in opposite directions: there is Jeremy Corbyn’s commitment to leave the EU (on a magic carpet of retained single market privileges), and there is party members’ preference for a referendum with a view to killing Brexit altogether. This election shtick is a capacious hiding place, accommodating opposition MPs who privately dread going to the country under a leader they deem unsuitable to be prime minister. There are also Corbyn loyalists who are impatient for the leader to table a vote of no confidence in the government, largely as a ritual that needs performing before party policy can be nudged in a more remain-friendly direction.

Parliament appears to have collectively reconciled itself to a period of constitutional mayhem

Only May has nowhere to hide. The prime minister has been forced to state a detailed case then see it trampled in parliament and in Brussels. She has been jeered at the dispatch box and cold-shouldered in the European council. While Tory backbenchers and opposition parties can trade in Brexit fantasies, May has been tethered to the mundane reality of negotiation. She has tabled plans in black-and-white and watched her enemies scrawl all over them in bright blue and red crayon.

Today Downing Street published an exchange of densely phrased letters between the prime minister and the two presidents of the European commission and the council, Jean-Claude Juncker and Donald Tusk. The EU duumvirate offered reassurance that the Northern Irish “backstop” is a device of last resort, not a final destination, and promised that every effort will be made to avoid it coming into effect.

That failed to satisfy Brexiteers, whose loathing of the backstop is rooted in pathological mistrust of Brussels. Juncker and Tusk write in the weird EU idiom that somehow combines arid technocracy and an idealistic spirit of continental collaboration. It is a style that has never had any purchase on the Tory imagination. The wreckers have not come this far to be won over by legalistic assertions of goodwill. Within hours of the letters being published, Gareth Johnson, an assistant government whip, had resigned, citing the incompatibility of his Eurosceptic faith and a frontbench obligation to back the deal.

There will be more twists before the big vote. Other MPs might begin to crawl out of their hiding places and say what they really think. Parliament appears to have collectively reconciled itself to a period of constitutional mayhem. There is talk of informal cross-party coalitions and procedural fixes (dastardly coups in the eyes of Brexiteer radicals) that would empower the Commons to direct government action. But to what end, no one can agree.

The only common theme is disappointment: with May, with Corbyn; frustration with the Commons speaker, John Bercow; with the deal; with the EU for not conceding more; with businesses for being gloomy; with civil servants for pointing out intractable problems; with the rest of the world for staring in dismay when they were supposed to be impressed. Things that were meant to be easy turned out to be impossible. An action that was supposed to assert independence from Europe revealed how national power is depleted once it is cut off from continental solidarity.

What was advertised as a strength has made Britain weaker. This is Brexit. There really is no other kind. A majority of MPs know it, but too many still skulk in the shadow of the truth. They worry that it offends the spirit of democracy to criticise a decision taken by referendum. They quail at the thought of another campaign to supersede the last one. But it is also an offence against democracy for elected politicians to stare disaster in the face and turn away through fear of saying aloud what they know Brexit to be: a mess, a mistake, a wrong turn, a dead end. That is the irreducible core of the thing. It has been hiding all this time in plain sight.

• Rafael Behr is a Guardian columnist