A newly discovered birth relative of mine, a Catholic priest, is an exorcist, from County Cork. The Exorcist came to stay on Wednesday. The next evening he was doing what he called “a fairly straightforward overnight identify, isolate, subdue and expel job” in Angel. He wasn’t allowed to talk about it, and knows I’m an atheist, so avoids putting us in situations where we’d argue. The Exorcist displays a natural diplomacy my Brexit-voting relatives could learn from.

But with his boisterous sense of humour, four pints nightly Guinness habit, and lifelong addiction to Viz comic, my Exorcist cousin isn’t anyone’s idea of a spiritual warrior. I introduced him to Sandi Toksvig, who he loves, at a radio comedy recording, when he’d come straight from an especially distressing Solemn Exorcism. Toksvig took one look at the portly Irishman, assumed I was joking about his line of work, and let loose that hysterical laugh she does on Bake Off when a poor old man ruins his pie.

Because he was still wound up from fighting what he believed had been a servant of Hell, the Exorcist and Toksvig nearly came to blows and had to be separated by Nicholas Parsons. I think that, after 30 years in the game, this is still probably my best showbiz anecdote by some distance, and is the only reason I still get invited anywhere for Christmas dinner.

The Exorcist displays a natural diplomacy my Brexit-voting relatives could learn from

I was glad of the Exorcist’s company on Wednesday as I myself had felt possessed, if only by a sense of confusion, all week. Last Sunday, I had written a deliberately silly article, comparing burning Yorkshire brushfires to the apparently combustible Shredded Wheat hair of Andrew Neil, which somehow went viral, Neil’s own indignant tweet about the column driving a further 24,000 people through to it.

Googling “This Week”, “Andrew Neil” and “Stewart Lee”, to try and find out what was going on, only brought me further stress. I had enjoyed appearing on Neil’s show in February 2014 with the Scottish Nationalist, and former Kane Gang frontman, Pat Kane. And yet now I saw that afterwards Kane had tweeted his followers to say, “Jolly end-of-term feel backstage. Got to meet the somewhat odiferous Stewart Lee.”

To be fair, I had just come straight from doing three hours on stage at the Leicester Square theatre, but it is a disturbing comment to read about yourself. One of the great things about Google, I think, is that years after a social interaction which you felt had been a success, you find that all the while the other people involved were fighting back their urge to vomit because you stank.

By the end of last Sunday even the Cameron-pig-sex fantasist, tax toilet fugitive, and former Conservative party deputy chairman Lord Ashcroft had accused me of having a “meltdown”, while Neil was tweeting some guy called “Tom”, apologising for “Venezuela”, and pleading, “Could you now get Guardian to delete some of the garbage it’s recently published about me?”

Something I didn’t understand was kicking off and I was out of my depth. So, you’ll forgive me if today, instead of inadvertently bringing down the wrath of the online “alt-right”, I share with you a true story that has been bothering me that I can’t quite make sense of. There’ll be nothing so divisive as Andrew Neil’s smouldering Shredded Wheat hair this week.

Ridiculously, the Exorcist is another person with an impossible job who, when the subject of standup comes up, says to me, “I don’t know how you do what you do. I’d go to pieces. You must have some balls.” He still won’t accept that what he does for a living, even though I think it’s all a delusion, is harder than talking about farts to strangers.

We watched a news report together saying that, since the Brexit vote, British people’s mental health has deteriorated rapidly compared to their European counterparts’. This came as no surprise to the Exorcist. “People who think they are possessed are canaries in the mine,” he told me.

“I know there’s a national mental crisis brewing when I have to order extra bottles of Holy,” the Exorcist continued, pouring himself another Guinness. “I’m getting through gallons of the stuff! Brexit has brought people down and weakened their spiritual defences. There’s folk thrashing about, foaming at the mouth, and some of them spouting Tourette’s level 1970s racist bollocks on top of it all. The lads in my department are run off their feckin’ feet.”

“Are you saying Brexit has let the Devil in?,” I asked the Exorcist, smirking. “You realise people will say that is the most extreme manifestation of Project Fear to date.”

“I’m not saying any more to you, Stewart Lee,” the Exorcist said, and suggested we agree on our usual compromise. And with that the Exorcist leant forward and did a fairly convincing impression of my own supercilious English tones. “People who think they are possessed are just displaying symptoms of mental health problems, and that if Brexit is exacerbating them, then there’s going to be more of these supposed ‘possessions’.”

I agreed, laughing, that yes, that was exactly the sort of thing I would say. “Well you’re wrong,” the Exorcist said, shaking now, “and let me tell you, once Brexit kicks in, not being able to get fresh mozzarella is going to be the least of your feckin’ worries. Don’t you see? This is what He wants. The Lord of the Flies. The Lie Father. Division. Social breakdown. Brother against Brother. That Mrs May. Your man Neil with his hair. People like them. They could have stopped this. They’re His servants and they don’t even know! And you just think it’s funny, you smug bastard!”

• London dates of Stewart Lee’s new standup show, Snowflake/Tornado, are on sale now: leicestersquaretheatre.com, with national dates to follow. He will also appear at a benefit for Resonance 104.4fm at London’s Bloomsbury theatre on 25 March with Tony Law: thebloomsbury.com/event/run/18108