The former Spice Girls singer said she didn't know how to express her grief at losing her father, Francis, in 1993, so she channelled all of her energy into her pop career.
She said: "Sometimes I don't think I would have been famous if it wasn't for my father's death because the pain of it, it was so painful and in the western world, when somebody dies, we don't have that, we're so formal nobody knew how to comfort me and I didn't know how to express it either.
"So I just turned all that pain into, 'Right, I'm going to make it' - and it wasn't until I left the band, I think that's when I started to really feel how much I missed him."
Geri, 37, also spoke about how she felt after pictures of her wearing her infamous Union Flag dress at the BRIT Awards in 1997 appeared on the front of a number of national papers, saying she was upset because her bandmates in the Girl Group - Melanie Chisholm, Melanie Brown, Victoria Beckham and Emma Bunton - were not included.
She told British TV host Piers Morgan: "On one hand I was going, 'Wow, everyone is looking at my dress, isn't that fantastic?' But then I'm quite mindful that there are four other girls standing next to me."
Geri left the Spice Girls in 1998 to pursue a solo career, and most recently released a children's book, 'Ugenia Lavender', in 2008.