The only non-murdered man who either dated or married a notorious killer is warning HBO -- trash talk him in the biopic starring Jennifer Lopez and he's suing your asses.
First, the backstory ... Charles Cosby infamously dated Griselda Blanco -- a Colombian drug lord dubbed the Cocaine Godmother who's tied to hundreds of murders, including the deaths of every man she ever dated, except Cosby. J Lo's playing Blanco for HBO.
Cosby wants NOTHING to do with the film ... telling TMZ there better be no references to him ... or else.
What's more ... Cosby -- who narrated a documentary about Blanco's life, "Cocaine Cowboys 2" -- says he's no Jennifer fan ... calling her unconvincing with no street cred.
And Cosby's got his own Griselda project ... a movie he's producing called, "Hustle."