Robbie Williams said he found scenes depicting his former relationship with All Saints singer Nicole Appleton “the most difficult bits” to watch in his new semi-autobiographical film Better Man.

The musical film is based on the true story of the rise, fall and return of British musician Williams, who is portrayed by a CGI chimpanzee.

“I think the bits with Nicky Appleton are the most difficult bits because everybody else in the movie was villainous in my life in some way or another, and she’s the only person that didn’t do me any harm,” Williams said on the BBC’s The One Show.

Singer Robbie Williams and girlfriend Nicole Appleton from All Saints march through London in August 1998 to urge the world's superpowers to back Princess Diana's campaign to ban landmines
Robbie Williams and Nicole Appleton in 1998 (Paul Treacy/PA)

“So when I watched that, I feel a sense of shame that I was her idiot boyfriend at the time.

“She didn’t deserve that, she’s a good person.”

The pair’s on-and-off relationship between 1997 and 1999 is dramatised in the film.

Williams has been married to Ayda Field since 2010 and the couple share four children together, while Appleton was married to Oasis rocker Liam Gallagher from 2008 until 2014, having been in a relationship with him since 2000.

They share a son, Gene, while Appleton also has a daughter, Skipper Hudson Haines, with partner Stephen Haines.

On the decision to have a CGI chimpanzee play him in the new film about his life, Williams said: “I love eccentricity and I love unusual and I love surreal, and it made complete sense to me as soon as he pitched it to me.”

Better Man is directed by The Greatest Showman filmmaker Michael Gracey, who told of Williams’ role in convincing Hugh Jackman about the music in the hit film.

Robbie Williams and Michael Gracey
Michael Gracey and Robbie Williams on The One Show (BBC/PA)

“Hugh, the whole time we were working on The Greatest Showman, kept referencing Rob, he could choose any showman on the face of the planet and every reference was Robbie Williams,” Gracey said on The One Show.

“So when I needed help convincing him about the music, I got Rob to do a video telling Hugh that the music was great, and it’s what convinced Hugh to move forward with the music that we had which is the music in the film today.”

Better Man is set for release on December 26 in the UK.