Immediately after the supreme court’s ruling on Tuesday, the attacks on the integrity of our judges began. Arron Bank’s Leave.EU instantly started spewing bile and casting aspersions on judges whose only crime was to uphold the law. Even the government’s response was to hint that the justices wanted to “frustrate Brexit”, which was dutifully reported on the front page of the ever-more Pravda-like Daily Telegraph.

Fresh from its attacks on parliament and MPs, the government set its sights on the independent judiciary. MPs suggested abolishing the supreme court, while anonymous sources warned of dire consequences for the judicial system.

However, politicians weren’t out of the crosshairs for long. Once parliament returned, the attorney general – putting on a show to save his job – decried us as a “dead parliament”. The PM went even further, suggesting that the way to respect the memory of Jo Cox, who was assassinated by a far-right terrorist, was to get on with Brexit. Watching MPs fight back tears to defend the memory of their friend, I wondered how much more we could take of this. To add insult to injury, when an urgent question was the next day, instead of apologising to MPs in the chamber, Boris Johnson chose to double down on his language at a private meeting with Conservative MPs.

For the last few years, a string of MPs have been the target of threats of assault, rape and even murder. This has affected MPs on both sides of the house and on each side of the Brexit debate. It has affected female MPs most of all. The mask had well and truly slipped this week by the time Dominic Cummings told a distressed Labour MP that if he wanted the death threats to stop, he should “vote for a deal then”.

Antoinette Sandbach MP in her office at Westminster. Photograph: Martin Godwin/The Guardian

I did vote for the deal, more times than our prime minister. It didn’t stop the threats, nor the lies on Twitter, or MPs from my own party abusing me to my face and smearing me behind my back. It didn’t stop me having to have six people cautioned and one sentenced this year for threats made against me.

The language of some Leave-supporting MPs is the same as the language in the threats I receive. When MPs talk of betrayal, the far right perks up. When they talk of traitors, my inbox fills up. I don’t need focus groups to tell me what parts of the prime minister’s rhetoric work. I just wait for the copycats who use his words to threaten me.

When the prime minister said he’d rather be “dead in a ditch” than extend article 50, the trolls and fascists paid attention. Jess Phillips, a brave and inspiring Labour MP, received a threat with exactly those words. When she stood up to the prime minister on Thursday, that very day someone was arrested outside her office.

Countless MPs have explained this time and again. Some Conservatives point to comments by John McDonnell talking about lynching Esther McVey as evidence that we’re all as bad as each other. While I condemn those comments without qualification, this whataboutery masks a serious problem: the far right is taking its cues from our leaders’ language, and it is the far right which has already assassinated one MP and plotted the murder of another.

Yet when an MP explained to the prime minister that his words would be repeated back to her in the form of threats to her life, he dismissed that as “humbug”. Johnson needs to recognise he is no longer a highly-paid columnist. He is, a political leader whose words are taken seriously, even when he doesn’t take them seriously himself. His words can move markets, soothe tensions or incite violence. Until he lives up to the reality of his actions, he lets down our country and puts his colleagues in danger.

Sir John Major in a speech this week said: “It means this government wishes to win re-election, by inciting opposition to the most important bulwarks of our state and its freedom. Their approach is profoundly un-Conservative and will do permanent damage to the reputation of the Conservative party”. I agree with him. Moderate Conservatives must speak out against this aberration from our valuesand stand up to this divisive and irresponsible approach. It is not just Conservative values which are undermined, but British values which are being destroyed.

• Antoinette Sandbach is the independent MP for Eddisbury. She was one of 21 Conservative MPs who had the whip withdrawn on 3 September after voting against the government