CBS has threatened to sue the author of a bombshell tell-all about the network’s hit reality show Big Brother after the writer accused the popular program of shocking wrongdoing. A cease-and-desist letter issued to author Brody Stuart-Verner on June 21, and now obtained by RadarOnline.com, shows the cable giant threaten the Big Brother fan over what it called “inaccurate statements” and “unsubstantiated claims” in his tome The Big Brother Bible: 25 Years of America’s Summertime Guilty Pleasure. Senior Vice President of Legal Affairs Andy Wong wrote: “CBS is exploring its legal and other option…