Read our exclusive Damian McBride interview

Damian McBride, the senior No 10 adviser who resigned after smearing senior Tories, has revealed that Gordon Brown was so angry when he learned about the slurs that “he could barely even speak to me”.

Talking about the affair for the first time, McBride told the Guardian: “I was brought down by the newspapers, and obviously my own stupidity.”

McBride was forced to quit after details of emails he sent to the former Labour aide Derek Draper were leaked to the press.

They contained salacious gossip about frontbench Conservatives, including speculation about David Cameron’s health.

“I let [Downing Street] down appallingly,” he says. “No 10 should have stuck the boot into me much harder.”

Recounting the weekend that the story emerged, he said: “It was running on the news that there was this scandal brewing, but not with any details. So I rang [Brown] and told him what was in the emails and that I knew I’d have to resign.

“I lost my dad three years ago. He was from a religious Scottish upbringing, very stern, and he would have hated reading those emails. I remember thinking, ‘Thank God my dad didn’t have to see this’, but the way Gordon reacted to me that day, it was as bad as telling my dad.” Brown “was just so angry and just so let down he could barely even speak to me”.

The prime minister’s former official spokesman, who was removed from his day-to-day briefing of journalists at the end of last year, said he was “sorry for the damage I did to Gordon and the reputation of No 10. And I’m sorry for the offence I caused to various people by writing those emails about them.”

However, he added he could not apologise for the fact the emails were printed “because that had nothing to do with me, and I never wanted it to happen. As far as I was concerned, those emails went in the bin shortly after they were written … and that’s where they should have stayed”.

Speaking about the aftermath of the affair, he said: “That is the only period when I went through what you would classically call an element of depression or sleepless nights.

“You feel genuinely devastated because of the impact you’ve had.”

McBride also confirmed he has kept an account of the weeks following his resignation and did not rule out publishing the diary. He begins a job as business liaison officer at his old school, Finchley Catholic High, in north London in a week’s time.