I’m a Londoner, born and bred. It’s in my blood. I can’t imagine ever wanting to live anywhere else. And being a member of the Labour party is much the same. I was 15 when I first joined and it’s where I met many of my closest friends. Being Labour is a big part of who I am.

That’s why last week has been the most distressing and depressing of my 33 years in the party. Every single Labour member, supporter and politician now bears a serious responsibility, towards those we want to help in society, to act quickly and decisively to pull ourselves back together.

The Labour party is without doubt the greatest political force for progress this country has ever seen. We rebuilt Britain following the second world war, with jobs and homes fit for heroes. We gave everyone access to world-class healthcare, free at the point of need, and saved it from Tory cuts. And we created a welfare safety net to support anyone who is sick, disabled or out of work.

We are the champions of liberal values – outlawing racial discrimination, decriminalising homosexuality and legalising women’s rights. And we are the guardians of dignity at work – legislating for health and safety protections in the workplace, backing collective bargaining and creating the minimum wage.

All Labour members and politicians stand together on a collective platform that would transform our country for the better – at a time when this has rarely been more desperately needed.

A Labour government would invest in our public services to create opportunities for the next generation – in education, the NHS, local councils and the police. It would build and modernise to enable our businesses to grow – leading to improved railways, green infrastructure and better, faster broadband. And it would help those in our society who have been abandoned: the working poor, the unemployed, and all those across the country who have been left behind by globalisation.

Britain desperately needs a Labour government to deliver for the many, not the few – but the events of last week have sadly made that less likely, not more. History shows that Labour splits lead to Tory governments. Last time Labour split we were out of power for a further 16 years. I dread to think of the consequences across Britain if we had to wait until 2035 for the next Labour government.

Brexit and its underlying causes are shaking the very foundations of British politics. Both main parties splintered in the same week for the first time ever. However, it is our responsibility to ensure that the Labour party emerges from these uncertain times ready to govern and able to attract those members of parliament who have left to return home.

The most distressing part of the past week for me was watching a friend, Luciana Berger, talk about the horrific antisemitic abuse she has suffered for months on end. Anyone who has spoken to her or listened to her will have seen how deeply it has hurt her.

Luciana is not alone. It’s devastating that so many Jewish people now feel that Labour – a party that should be their natural home – does not have their best interests at heart, and worse, seems to them to be unwilling to tackle the scourge of antisemitism within.

Over the last few years, it’s clear that Labour has been too slow at addressing the Jewish community’s concerns and at kicking out the minority of Labour members and supporters who think it is acceptable to use antisemitic tropes and abuse – both online and in local Labour meetings. This has led to a collapse in trust between Labour and the Jewish community.

It’s so depressing that more Jewish parliamentarians, members and organisations with a long affiliation with Labour are now saying they are considering leaving. We must not let this happen. The Labour party must make whatever changes are necessary to make Jewish people feel at home in our party again. There is a long and proud history in our country of people from the Jewish community supporting social democratic and Labour values, with the Jewish Labour Movement first affiliating to the Labour party back in 1920.

Sadly, it’s now possible that the Jewish Labour Movement will never reach its 100-year anniversary. As Labour’s mayor of London, I will do everything possible to ensure they stay. Over the coming days and weeks, I will continue to meet with the Jewish Labour Movement and representatives of the wider community, to reassure them that – like many other decent people within our party – I’ll fight on their behalf to keep Labour their political home. Everyone in our party must do the same.

While we inside Labour have been shaken by events this week, the real world hasn’t stopped. The very real threat of a catastrophic no-deal Brexit in just a few days makes the need for us to unite even more urgent. The people we exist to help need us to be a strong, coherent opposition to this reckless government.