It was a politely furious protest. I’ll talk about the politeness first. I arrived a few minutes late to Parliament Square for the demonstration against … well, let’s say the somewhat cavalier attitude towards antisemitism displayed by various members of the Labour party, and specifically the most senior member of the Labour party. The square was jam-packed, and despite all the people on my social media feed who had been urgently telling me for days that Jews were hysterically conniving to bring down Jeremy Corbyn, there was a notably peaceful air to the proceedings. While speakers such as Luciana Berger tried in vain to make themselves heard, the crowd made self-mocking jokes: surely there must be a buffet at a Jewish protest? I wished I’d made some signs: “Not antisemitic? Jew must be joking!” It was that kind of protest.

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But there was also palpable fury beneath the politeness. I can’t speak for why all the other people at the protest felt furious – we didn’t establish a party line on this at our last general meeting because we were too busy discussing how to control the weather, as a US politician alleged last week. But I was furious after a weekend of news stories about how Corbyn had, once again, endorsed antisemitic behaviour and failed to take responsibility for it until public opinion forced him to do so. Deja vu? Groundhog Day, more like.

Let’s run through the greatest hits: there was the time Corbyn took tea with the hate preacher Raed Salah, and called him “a very honoured citizen”, even though he’d been charged in Israel with inciting anti-Jewish racism and violence; the time he hosted representatives from Hamas and Hezbollah, even though Hamas’s charter calls for the destruction of the Jews; the times he accepted a total of £20,000 for appearing on Iran’s Press TV, a channel that regularly hosts Holocaust deniers; the time he defended the Rev Stephen Sizer, who was later banned by church authorities from social media for sharing antisemitic material blaming Israel for 9/11; that he was an active member of three Facebook groups on which deeply antisemitic posts regularly appeared; and that now he has commented on Facebook in support of an absurdly antisemitic mural. Corbyn is frequently praised by his supporters for sticking to his guns, never wavering in his opinions, and yet when you bring up any of the above instances they wave them away as being “ages ago” and say he’s apologised since. Corbyn has always cried innocent, insisting that of course he abhors antisemitism (and-all-other-forms-of-racism). How could anyone accuse him of being soft on it? Don’t they know his mother was at the Battle of Cable Street? Yeah, well, my mother worked with Jim Henson – it doesn’t make me Big Bird.

Truly, I have never known a man to find himself alongside antisemites so often and not realise until it is publicly pointed out to him. Someone ought to make a sitcom about his misadventures with the antisemites. It could be called Oh, Jeremy Corbyn!, but with a more tutting tone than the usual triumphant one. A descending horn noise could sound whenever someone has to say it: “Have you just joined another antisemitic social media group? Oh, Jeremy Corbyn!”

I was furious after a weekend of watching his supporters – members of the public, journalists I once respected, various MPs – insist that this was all nonsense, a smear, a Zionist conspiracy designed to bring down infallible Jeremy. Quite how Jews have the wherewithal to conspire against Corbyn by cunningly making him endorse antisemites without his knowledge is never explained. So let’s get something straight: if someone has actually done something, reporting that action is not “a smear”, it’s “reporting”. And suggesting Jews always have an ulterior motive, even when reacting to antisemitism, is really not the best way to prove that you’re not antisemitic.

I’m furious with people who respond to these points by huffing that criticism of Israel, by Corbyn or anyone on the left, does not make one antisemitic, even though Israel had nothing to do with any of Corbyn’s antisemitic encounters; and I’m furious with people who imply a little antisemitism is a price worth paying to achieve Corbyn’s socialist society. I’m furious with people who spent all of last week reading Russian runes into an image of Corbyn’s hat on Newsnight, and this week insist they can’t see anything antisemitic about a blatantly antisemitic mural. Most of all, I am furious with people for insisting there is nothing to see here, when we all know that if a Tory or Ukip politician had done half of the things Corbyn has done, these same people would be insisting they be put in the stocks. The hypocrisy takes the breath away.

I’m furious with people making Corbyn seem like a passive participant in all this

Finally, I’m furious with people making Corbyn seem like a passive participant in all this. Sure, we can talk about how antisemitism is “baked into” the far left, and Corbyn himself has started to push this narrative with his latest apology (his third, or possibly his fourth since Friday – I’ve lost count). He says “antisemitism has resurfaced within the Labour party”, as though it were nothing to do with him, and others refer to antisemitism as a sickness that they will now root out.

But you cannot help getting sick – you can, however, help turning a blind eye to antisemitism. Corbyn made his own choices about what he clicked online and who he had tea with. What Jewish people need is for him to take some responsibility, show some backbone and honesty, explain why he was willing to ignore antisemitism for so long, and apologise. Not for “feelings hurt”, but for endorsing racists.

But I’ll be honest, I’m not holding my breath. So in the meantime, going to the protest was a balm. It was a relief to be with people who weren’t gaslighting Jews by insisting that what they were seeing in front of their eyes wasn’t true, and it was nice to see the MPs who showed up – Harriet Harman, Jess Phillips, Stella Creasy, Chuka Umunna – and know that at least some Labour politicians weren’t laughing this off as a distraction.

By the time Labour MP Wes Streeting took the stand to talk about how this ongoing scandal was “a stain” on the Labour party, and that Shami Chakrabarti’s 2016 report into antisemitism in the Labour party was a laughable “whitewash”, emotions were running high. No yarmulkes fell off any scalps, but you could see the backs of necks pinking. It was a civil protest, but a passionate one, and a deeply serious and heartfelt one. And as I left I felt myself smiling a little. But I’ll be honest – I was still furious.

• Hadley Freeman is a Guardian columnist and feature writer

• This article was amended on 28 March 2018 to clarify the chronology. Jeremy Corbyn defended the Rev Stephen Sizer before Sizer was banned by church authorities from social media for sharing antisemitic material blaming Israel for 9/11