Ant and Dec considered splitting up after Ant McPartlin’s conviction for drink-driving last year, the pair have told the Guardian in an exclusive and wide-ranging interview.

McPartlin was more than twice over the legal limit when he smashed into two other cars in south-west London last March. He was driving his mother, and both cars he hit contained children. McPartlin was fined £86,000, believed to be a British record for drink-driving, and banned from driving for 20 months.

Declan Donnelly said McPartlin’s drink-driving offence was “indefensible”, and that when he heard about it he was angry with his friend as well as upset for him.

The exclusive interview will be in Saturday’s Weekend magazine. Photograph: David Vintiner/The Guardian

When asked if he had considered separating from his on-screen partner of almost 30 years, he said he would be lying if he had not thought about it, but that ultimately he wanted his partner healthy and happy, and the relationship back on track.

After the crash, McPartlin announced he was immediately withdrawing from his television commitments and going into rehab.

They said that they then reassessed their career and relationship. They realised they had started to take each other for granted, and had stopped talking to each other properly. “For the first time in many years, all we talked about were deep things like how we felt, and what the future held, and where we were, and all the chaos that has come along, especially for me,” McPartlin said.

The presenters are due to return as a TV duo next Saturday for the first time in a year on the ITV show Britain’s Got Talent.