It's the moment Nicollette Sheridan has been waiting for ... she's finally inside an L.A. courtroom, waiting to unleash hell on "Desperate Housewives" creator Marc Cherry for allegedly smacking her on set ... and then firing her from the show.
TMZ broke the story ... Sheridan sued the "Housewives" creator ... alleging he smacked her across the head and face on the set back in 2008 ... and after she complained, he fired her. Sheridan is demanding millions of dollars in damages.
Cherry is adamant Nicollette's making the whole thing up ... and several past and present "Housewives" cast members, including Eva Longoria and Dana Delany are standing by their man.
Opening statements are expected to begin any moment -- stay tuned.