The 46-year-old pop star was threatened with being sacked from the Spice Girls after she was seen arguing with Victoria at the BRIT Awards in 1996 and Mel - who was read the riot act by the group's manager - has now admitted the incident had a detrimental impact on her mental health.
Appearing on BBC Radio 4's 'Desert Island Discs', the singer confessed: "I was so hurt and embarrassed. We'd all had a few bevvies and on the way out there was a little scuffle between myself and Victoria.
"We can't say this on air but I asked her to go away. I was told if that behaviour ever happened again, then I would be out."
Mel - whose real name is Melanie Chisholm - knows she could have easily thrown away her career.
As a result, Melanie became more self-disciplined than ever before - which prompted her mental heath struggles.
Mel - who has also battled an eating disorder - shared: "To think I could have messed that up and lost it all ... I began to be really, really hard on myself.
"I think that is where the start of some of my problems came because I had to be very, very strict with myself. I couldn't allow myself to relax because if I did I might mess it all up."
Mel also confessed she struggled to live up to her Sporty Spice persona.
She said: "I think I was described as the plain one at the back that doesn't really do much or doesn't really say much.
"That is really hurtful when you are a young aspiring pop star. I tried to make myself perfect, whatever I deemed perfect to be."