What cowardice. She roused the country to the great climax of Tuesday’s parliamentary vote on her EU withdrawal deal, only to beat a retreat – yet another fateful error in Theresa May’s miserable, blundering leadership. This vote was set to be the cathartic moment when the country finally faced the Brexit truth. The cataclysmic collapse of May’s deal would have wiped the slate clean for her, for every MP and every party, freeing everyone to think again. Yes, hers was the only deal possible – but only if she was right that the nation’s ultimate uncrossable red line really is stopping immigration and free movement. If closing our borders is non-negotiable then hers was the only deal, whoever was prime minister. But that deal was set for a parliamentary defeat no government had suffered in living memory, with public opinion overwhelmingly against.

Never mind her personal fate – leave political obituaries for another day. The country has to ask whether curbing EU immigration still matters above all else. If so, then the only other option is crashing out with no deal, whoever is leader. But a no-deal crash is so dangerous, the great majority of MPs will absolutely reject inflicting an 8% fall in living standards, blocked ports, empty supermarket shelves, medicine supply failures and the pound falling through the floor – it even slumped on news of this postponement. As it plunged, the madness of the ultras was captured by John Redwood telling Bloomberg TV not to worry, as a no deal saves the £39bn divorce fee: “We won’t be crashing out, we’ll be cashing in.” Most MPs of all parties will refuse to underwrite such an act of suicidal idiocy.

As the Tory axemen sharpen up to decapitate their leader, the rest of us must sincerely hope she survives. She may be our most inept prime minister in living memory, apart from David Cameron who caused this mayhem, but far worse beckons, whoever replaces her. If 48 Tory MPs send in their letters, and 158 or more of them vote to oust her, we should fear the even worse leader their party will elect instead. Whatever their original EU stance, the winner will have campaigned for the votes of the ageing Brexity shire members of their small party, each contender out-Brexiting the rest with harder pledges. Some – Boris Johnson, certainly – will promise to crash out, and that may get him anointed. Others will promise undeliverable unicorn deals, cake-eating, cherry-picking, that can only lead to the identical crisis May faced once she found her red lines made any deal with the EU impossible. Pray she stays: after all her errors, she at least now knows some basic EU truths.

Off she goes to Brussels to pretend some cosmetic rejigging will solve the Irish border backstop, though the taoiseach, Leo Varadkar, said on Monday that it was not possible. If the EU gave way, Varadkar’s government would fall. Of course Brussels will rightly favour supporting him over propping up Britain’s disgraceful Brexit government.

An election is improbable but not impossible – though Jeremy Corbyn stands accused of failing to call a confidence vote. Any sane Tory would run a mile: if they offered themselves to the nation in their present shambolic state they would suffer a well-deserved defeat. They could agree no manifesto stance on Brexit, with their platforms a comical tug-of-war between at least four factions.

Labour would finally have to resolve its conflict between Corbyn’s small coterie and virtually everyone else, Momentum included. A fudged “we will renegotiate” will fall apart in the first week of any campaign. Of course Labour should stand as remainers against Tory Brexiters. Look how Caroline Lucas mocked them in the Channel 4 debate: “Brexit is a project for the right, by the right and why Labour would support it I just don’t understand.” But if, lamentably, that’s a step too far, then a Labour manifesto has to promise a referendum – letting the people solve their indecision is the only way to hold the party together.

Every day, a referendum looks more likely – it would be the only escape from this car crash. “Hell will freeze over before May agrees,” an ally of hers says – but it is now the last escape hatch from this hell. The Brexiters’ own “project fear” has been to terrify the nation, threatening that any attempt to run another referendum would cause rebellion, mob-rule, riots on the streets. What are they so afraid of? It’s losing, now that the polls are shifting.

The country will not be intimidated by the absurd idea of people rioting against getting the chance to express themselves in a democratic vote. Watching the Ukip/Tommy Robinson march on Sunday, I saw nothing much to fear. Outnumbered 10 times by anti-racist, anti-Brexit marchers, they were a familiar little group rallying to Robinson’s boasts that “no other politician will talk about Islam”. They were mostly men, mostly middle-aged. The most notable thing about them and their “Brexit betrayal” banners was the low turnout. The “Out! Out! Out!” shouters, familiar thugs failing to find a fight, were outnumbered by ordinary people from that ordinary strand that is not just British, but found in every country.

How familiar is that “keep Britain white” surge, whether it comes dressed as BNP, EDL, National Front, Combat 18, National Action or any of the other groupuscules that always implode. Whatever happened to Enoch Powell’s rivers of blood? We are where we are because Cameron’s crime was to call a referendum on foreigners and borders that predictably gave a legitimate outlet to that seam in the psyche of any country. Even more grotesque has been the Brexiters using Robinson shamelessly as their advance guard, and Iain Duncan Smith warning any second referendum will cause Paris-style riots. Even Brexit-convert Jeremy Hunt uses them to avoid a vote: “I wouldn’t rule out real social instability in this country.”

The question now is how to put all the dark passions and fears Brexit aroused back in their corner. It needs firm leadership, a rejection of racism, and someone who will take no nonsense about riots. No one but the voters can reverse what has been done, now that Brexit in all its fiendishness has been explored and found miserably wanting. Promises turned to dust. Both sides have been preparing their referendum campaigns. The Brexiters will rely on a simple but clever “Tell them again!” while remainers plan a positive “Europe works” and a negative “Did you vote to be poorer?”

May will try to defer this vote until the last possible day to force a “her deal or no deal” choice. Instead she has just inched the possibility of no Brexit at all closer to the finishing line. The Treasury had better put on hold that promised 50p coin to commemorate Brexit day.

• Polly Toynbee is a Guardian columnist