Paul Anthony Kelly , coming off his breakout role as JFK Jr. in Ryan Murphy ‘s Love Story: John F. Kennedy Jr. & Carolyn Bessette , is reuniting with Murphy in the upcoming 13th installment of FX ‘s American Horror Story . Kelly’s casting was announced Tuesday during Disney’s upfront presentation in New York. AHS cast members Sarah Paulson, Evan Peters, Angela Bassett, Gabourey Sidibe, Billie Lourd and Emma Roberts were onstage, flanked by hooded Druids, when Kelly emerged from the shadows to reveal his addition to the cast. “I guess every nightmare needs fresh blood…and thirteen’s my lucky number,” he added. Per usual, details are under wraps for Season 13. Kelly is joining a cast that includes Roberts, Paulson, Sidibe, Lourd, Peters, Bassett, Jessica Lange, Ariana Grande, Kathy Bates and Leslie Grossman. Watch on Deadline Created and produced by Murphy and Brad Falchuk, American Horror Story is FX’s longest-running hourlong series and has amassed more than 100 Emmy nominations since its 2011 launch.…