Shane Lynch "hated" Ronan Keating "with a passion".
The Boyzone singer was devastated when the band decided to go their separate ways in 2000 to work on their solo careers, and he admits he blamed his co-member for the split, but he believes they've changed their ways since then.
He said: "[I] hated [Ronan] with a passion.
[It's more] cups of tea and hugs [now]. We were reared on the quiet side of the tracks. We were nice lads, none of us were the tough guys in our area. We got together, went off in our own bubble and we were on an exciting rollercoaster."
The group, consisting also of Keith Duffy and Mikey Graham, will rejoin for their one-off special TV appearance '20: No Matter What', for their 20th anniversary, and are ready to take to the stage without their other member Stephen Gately, who died in 2009 from an undiagnosed heart condition.
Mikey explained: "The memories will always be there, but we've managed since Stephen's passing to accept the new shape of Boyzone, and to build upon that slowly."
Ronan added: "It's mad, Warner Music are doing a four-album deal [with us] so it doesn't mean it stops here, it's only just started.
However, the 'No Matter What' hitmakers aren't sure their dance moves are up to scratch anymore, but they have promised they will continue performing as long as fans are still buying their records.
Mikey said: "As long as we have fans who buy our records and want to come and see us perform, why not? But I don't know if we'll still be doing a lot of dancing at 40 though!"