The 'Monster' hitmaker admits he was disappointed with the music he was writing before he recorded 'The Marshall Mathers LP II' and it "hurt" when he listened to rappers like Kanye who were doing well in the industry.
He told radio station Power 106: "For that time period that I was away, I was watching what was going on in the game. Anything that was hot at that moment, anybody that was really killing sh*t. I felt so bad about myself and the music that I was creating, I felt like I was starting to turn into a hater.
"Singling Kayne and Wayne out at that time period, they were the ones killing it the most to me, and it hurt. I popped a CD in and be like "f**k man, I'm not doing this no more."
He thought about writing and recording a song "dissing everybody" but knew it would be career suicide and decided against it.
Asked if he already had the verses written down, he replied: "I just had the thoughts walking around the studio, deep down I just wasn't happy with myself. There were some pretty dark moments in there man, when I think about my thought processes, when I was high a lot, it wasn't good, it certainly wasn't me."
Eminem didn't think he could make good music being sober before he went to rehab and "couldn't do anything" without being high.
He added: "It was to the point where I was taking pills just to not feel sick."