The girl group announced they would go their separate ways after their Ten: The Hits anniversary tour ended last month, and Sarah was surprised by Nadine's reaction, tweeting she ''couldn't stop'' the other members ending the band and she wanted to continue.
Sarah told Look magazine: ''I was unaware she even felt like that. At no point did she try and stop us, so you'd have to ask her why she did that.
''We all had other things in the pipeline for after this tour and wanted it to be the biggest and best show we'd done. We'd rather do that than keep putting out more and more music every year and gradually waning, because music's evolved since we've been around. I'd hate to think we'd end on a bad note.''
She added: ''We were more grown up and more opinionated, and when there were discussions to do with work we'd all be sort of strategic.
''Me and Nadine are more music orientated - more vocals - and the other three are more about dancing. I'd put my foot down about the music side of things. Nicola was more about the clothes. Choreography is Cheryl's forte.''
Sarah also said she is now looking forward to her solo career and having more input into the different aspects of her live shows.
She added: ''When there's five of you, it's difficult to have a say in everything. I'm looking forward to having more control.''