In his song Eminem commonly talks about 'Slim" as all his bad qualities, and the cause of all his problems. He actually kills him of in the song "Mockingbird". After Eminem kills him, everything gets better.
He killed "Slim shady", his alter ego.
"Slim Shady, hotter than a set of twin babies"
"I'm Slim Shady, yes i'm the real Shady"
"Slim Shady does not give a fuck what you think"