Melanie Chisholm has said her daughter gave her the strength to leave her ex-partner.
The 46-year-old Spice Girl, also known as Sporty Spice, was in a 10-year relationship with property developer Thomas Starr until 2012.
They share a daughter called Scarlett who was born in 2009.
Appearing on Desert Island Discs, Chisholm said becoming a mother had “changed” her.
She added: “She has made me braver. She has made me stand up for myself more.
“I make big decisions. Leaving her dad was hard but I wasn’t happy and she wasn’t happy, and it wasn’t the environment I wanted my child to grow up in.
“I couldn’t have done that without the strength that I got from her.”
The star broke down in tears as she told host Lauren Laverne how she came to become depressed and develop an eating disorder during her time in the Spice Girls.
She also said she had felt betrayed by her dad after discovering he had fathered another daughter in secret.
“My dad worked away a lot so my mum did all the tough stuff,” she said.
“My dad – I saw him at weekends and I went away in the summer with him. He was the wonderful dad who I did all the fun stuff with.
“I had him on this pedestal. Then he had kept a secret from me for 15 years and it took me a few years to get over it because I felt betrayed.
“I kind of felt my childhood had been a bit of a lie.”
Chisholm was in her 20s when she met her 15-year-old sibling for the first time.
She continued: “Now it’s a wonderful positive thing as I adore her and I have two beautiful nephews. There’s a really happy ending but it was a really difficult beginning.”
The wide-ranging interview also touched on her working class upbringing in Lancashire and Cheshire, and the early days of the Spice Girls, which were originally called Touch.
Chisholm said the group had made the idea of feminism “more digestible for young people”.
She added: “It’s wonderful to see generations growing up feeling empowered by us being up there, doing the things we were told we couldn’t because we were girls.
“I think that really is the legacy of the Spice Girls.”
Geri Horner, or Ginger Spice, shocked the world when she quit the group in 1998, citing “differences between us”.
Chisholm said her departure left them “absolutely devastated”.
She added: “And we really thought she would come back. But for reasons – her own reasons – she had to go. That was the time she had to go.
“I completely respect that now but at the time it was really difficult. And in all honesty, (it was) the beginning of the end for the Spice Girls.”
Chisholm selected tracks including Stevie Wonder’s I Wish, Fleetwood Mac’s The Chain and Madonna’s Into The Groove.
Her special object was a vintage Martin acoustic guitar and for her book she chose the Dusty Springfield biography Dancing With Demons by Penny Valentine.
Desert Island Discs airs on BBC Radio 4 and BBC Sounds on Sunday at 11.15am.