I will be returning, exhausted, on the last train from Madrid to my home up in the Guadarrama mountains.
On Friday evening, EuroCitizens is meeting to discuss the impact of the Withdrawal Agreement on our lives: how it will guarantee some of our rights and how it will take away others.
We will be updating members on Spanish nationality issues and explaining how we are trying to get clarity on Spanish government measures for Britons during the transition period.
As the train halts in neon-lit suburban stations to disgorge late commuters I will be sad as well as tired. Sad to see my country leave the European Union after nearly fifty years.
Sad to witness the rising tide of narrow nationalism, bigotry and intolerance that is swamping Britain and elsewhere.
Sad that five million citizens, Europeans in the UK and Britons in the EU, have had to suffer years of excruciating uncertainty to get to this point.
Sad that 1.2 million people have lost their European citizenship against their will. Sad because thousands of young Britons in the EU will be unable to study or work in another country. Sad that the professional futures of people who I know will be blighted by restrictions on cross-border service provision. Sad about the complete futility of Brexit.
Ten minutes before getting to El Escorial, the shopping centres, serried rows of semis and bleak, empty car parks will stop and the train will traverse meadows and woodland hidden in darkness.
My spirits will rise and I will think of those who I have worked with in the struggle for citizens' rights. My fellow Europeans in Britain who, through the3million campaigning group, have fought so bravely against Theresa May's hostile environment and pressured the UK government to treat EU citizens decently.
I will mull over the previous hectic week at British in Europe, which started early on Sunday morning and still has not finished. Ten people working flat out for ten hours a day without pay: completing reports on the Withdrawal Agreement, preparing a crucial lobbying trip to Brussels, meeting officials and politicians, catching early-morning buses and late-night flights, sending out newsletters, posting online, finalising budgets and coordinating grassroots groups.
When we finally roll into the station it might be too late to raise a commiserating glass. But I will have done that a couple of hours earlier in the company of my friends and colleagues in EuroCitizens.
I will remember that the best, perhaps the only, way of facing disappointment and adversity is with other people. I ask you to do the same, to support British in Europe over the coming months, to help us ensure that Britons are treated fairly by EU member states, that our rights are fully respected and that we claw back some of the rights which have been stolen from us.
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