Next week the prime minister hopes to take a step forward in her government’s negotiations to leave the EU. Whether we voted leave or remain, all of us have an interest in ensuring progress is made. The talks come on the back of a scarcely believable transatlantic diplomatic row, with President Trump’s completely unacceptable retweets of the fascist, hate-fuelled Britain First and his subsequent public rebuke of Theresa May on Twitter.

The prime minister of course rushed to extend the hand of friendship – literally – to Trump when he was elected, and she is right to ensure that the deep, longstanding links between these islands and our friends in the US endure. But surely she must now accept the enormous folly of hoping that a trade deal with the Trump administration will somehow come even close to replacing the lost trade, jobs and investment caused by taking Britain out of the EU single market and the customs union.

Seventeen months have passed since the referendum, but incredibly the UK government is still scrabbling to reach agreement on the three key separation issues – never mind begin negotiations on a trade deal. I remain firmly opposed to Britain leaving the EU, and continue to hope that not just Scotland but the UK as a whole will choose an alternative to this monumental act of social, economic and diplomatic harm.

But if Brexit is to happen, then it must happen in a way that limits the damage as much as possible. The unedifying experience of the past few months – with irrational and unreasonable threats of no deal, insults flying across the Commons chamber and across the Channel, and the utterly despicable attitude and ignorance of the extreme Brexiteers towards Ireland and Northern Ireland – is only adding to the harm being done by the Brexit decision to the UK’s reputation at home and abroad.

It appears that to get to phase two of the negotiations the Tories will have to accept everything they have wasted six months rejecting. The bill has to be paid, citizens’ rights have to be protected, and Ireland can no longer be ignored. These issues must be resolved, but making sufficient progress should not be seen as the end of the process – the talks over the future relationship matter just as much, if not more.

As we head into another year of Brexit talks, it’s time to banish the language that characterises the EU as our enemy

This week an independent thinktank highlighted that 134,000 jobs in Scotland depend on our trade with the EU – but those are already under threat before Brexit takes place. Businesses are pushing for answers on transition. They need certainty as soon as January to make the right decisions, and the overwhelmingly preferred option is for a steady-state transition – in the single market and customs union.

Yes, that will mean accepting the jurisdiction of the European court of justice; but to continue to put ideological totems before the jobs of hundreds of thousands of people would be to compound and accelerate the damage Brexit will do.

So far we have seen decisions taken in the interests of appeasing Tory Brexiter backbenchers. But ultimately, in the absence of a Labour party that will properly oppose Brexit, the UK government already has its way, so now it is time for the economy to come first.

The prime minister needs to come away from the EU summit with a clear agreement to move into trade talks and a clear statement that transition will mean remaining in the single market and the customs union – nothing less. Warm words and cryptic soundbites will not suffice when companies are beginning to make real decisions that will impact on people’s jobs. And that transition must not be simply a two-year postponement of falling over a Brexit cliff edge. It is an opportunity to recognise a better way forward.

Last December the Scottish government published what is still the most detailed analysis by a government in the UK of the way forward. It concluded that for the UK and for Scotland, short of EU membership, the best answer to the Brexit problem is to remain in the single market and the customs union.

In the new year we will publish updated analysis – a proper impact study of the options – that sets out the benefits of the single market, not just now but crucially in the years ahead as Europe develops a digital single market and opens up new opportunities in energy and other areas. And crucially, in a way the UK government has so far failed to do, it will set out the impact of choosing not to be in the single market. Labour’s claims of a “jobs-first Brexit” will be shown to be nothing but bluster if it cannot speak up loudly and clearly in favour of the single market.

While it isn’t perfect, the single market protects workers and environmental rights; allows us to work, study, and live in other countries; brings investment into the UK as a whole; and at a stroke solves the challenges on the island of Ireland. It is without a doubt still, after all these months, the best way forward.

Scotland did not vote to leave the EU. The decision is one that many in Scotland have not reconciled ourselves to, and cannot. There are many people across the UK who – like me – have been watching events in Westminster in recent months with a mixture of frustration and disbelief. As we head into another year of Brexit talks, it’s time to banish the language that characterises the EU as our enemy, and instead approach the next phase of talks in a spirit of cooperation and solidarity of benefit to us all.

There is one way to make that change of attitude crystal clear. If talks in the next 10 days fail to make sufficient progress to move on to trade negotiations, the EU and the UK should at least confirm that citizens’ rights remain intact across the EU and the UK, and give families some sense of certainty over their futures.

• Nicola Sturgeon is first minister of Scotland and leader of the SNP