Charlie Simpson thought he'd "turn to drugs" if he didn't quit Busted in 2005.
The 'Year 3000' singer has rejoined his former bandmates
Matt Willis and James Bourne in the British pop/rock band and has revealed he was afraid he would become dependent on narcotics and alcohol because he was feeling very "depressed".
Speaking in an interview with Kerrang! about why he walked away from the super-successful group first time round, he shared: "I don't want to sound too extreme but was as close to getting depressed as you could ever get and I was worried I might turn to drunk or drugs or something. It was really nothing to do with Matt and James."
Charlie went on to form alternative rock band Fightstar but always felt guilty about his decision to leave his old friends.
He said previously: "I felt a huge amount of guilt when I left Busted the first time because I knew that they didn't want to stop and that was hard to deal with. We were really good friends and you don't want to upset anyone you care about. But staying in the band at that time could have risked our friendship."
Charlie's bandmate Matt did end up having a stint in rehab to be treated for alcoholism in 2005 following Busted's break-up.
The musician - who is married to Emma Willis - also sought help for cannabis abuse in 2006, but has been clean and sober ever since.