In February, when the documentary maker Dan Reed and I met in a near-empty bar, it felt very much like the lull before the typhoon. He was calm and expansive as he spoke about his film, Leaving Neverland – which was about to be broadcast – about James Safechuck and Wade Robson, who accused Michael Jackson of sexually abusing them for years.

As I looked at him leaning back, relaxed as you like, talking casually about “the Jackson fans”, I thought: “Sonny Jim, you have NO IDEA what you’re getting into.” It was like watching an innocent babe wander into a dark wood, the sounds of snarling animals in shadows all around him.

Well, 10 months later, the innocence is truly gone. The documentary completely shredded what was left of Jackson’s reputation, but that didn’t stop plenty of people putting up a fight in his defence. True to form, members of the Jackson family went on the attack, casting aspersions on Robson, in particular. Jackson’s most-dedicated fans, not known for their rationality, eagerly went after Reed especially, but really anyone who dared to express a sceptical opinion about St Michael. On the day my interview with Reed, Safechuck and Robson went online, I had to block more than 100 Twitter accounts. I couldn’t even imagine how Reed used the internet at all any more.

Dan Reed: ‘As soon as the movie was announced, people were denouncing the victims without even knowing who they were.’ Photograph: Channel 4

But Reed is a man with pride. So, when I ask him how he coped with thousands – maybe even tens of thousands – of people telling him he was a dupe, a bad journalist, a liar and deserved to die, he replies: “I don’t want to sound blase, but I’ve received unwelcome attention from people I’m a lot more frightened of than Jackson fans – people from the criminal underworld and terrorist organisations [whom Reed has also made films about].”

Nonetheless, he admits, he was “surprised at how unceasing the torrent of abuse was”, including reams of threats and emails to his film company, and especially the smearing of Robson and Safechuck. When Reed gave a talk at the Edinburgh festival, Jackson fans protested outside – “with signs saying ‘MJ Innocent’ ... the usual shit,” he says – and one day they parked a van outside his office and blasted Jackson’s music.

“I wasn’t even there so it was a bit of a waste of time. I only found out about it because they made a video of it and posted it on Twitter,” he says. “As soon as the movie was announced, people were denouncing the victims without even knowing who they were. It was just a kneejerk reaction: these guys are liars. And you can’t challenge them with facts because it’s an article of faith for them and any challenges to that belief are blasphemy,” he says. The Jackson family, he points out, have not made any factual challenges: “They just say: ‘Our brother was a lovely guy.’” As a result of his experience in the maw of Jackson fandom, Reed is now thinking about making a documentary about other kinds of denialists.

He no longer looks at his mentions on Twitter – “there is no point” – and Robson and Safechuck pretty much stay away from social media entirely. “It gives them a measure of calm. I’m amazed at how serene they’ve been through all this. But the movie has been good for them: they feel like their story has been told and entered the public conversation. I think people who saw the movie found Wade and James very credible.”

Robson sued the Jackson estate in 2015, but a judge ruled that too much time had passed. He tried again in 2017, but it was decided that the corporation was not liable for Jackson’s personal activities. According to news reports, Safechuck and Robson, buoyed by public support, are again trying to take the estate to court.

A protest against Dan Reed and his film outside Channel 4’s offices in London in March 2019. Photograph: George Cracknell Wright/Rex/Shutterstock

After Leaving Neverland aired, there was much talk about whether people could still enjoy Jackson’s music or whether he would be cast on to the same reject pile as Gary Glitter. Reed was never especially interested in this argument: “I’m not about cancelling Jackson. But I think people should know that he was, at times, a monster to children,” he says.

How does it feel if he turns on the radio and a Jackson song comes on? Reed laughs: “You know, I didn’t listen to pop music growing up, so I was never very good at recognising his music,” he says. And then, as if he hasn’t outraged Jackson fans enough already he adds, with a final knife twist: “I didn’t even know, until halfway through production on the documentary, that Billie Jean was a Jackson song.”