Eminem is gearing up for intense reminiscing ahead of the pending release of Mariah Carey’s upcoming memoir.The “Lose Yourself” emcee – whose real name is Marshall Mathers – reportedly dated the “Emancipation of Mimi” songstress in the past and word has it that the real Slim Shady, 47, is expecting Carey, 50, to divulge on their relationship.“Eminem’s Achilles…