Complex sentence: Melmoth refused to speak the opera's epilogue, as she disapproved of its patriotic sentiments, leading to the New York Journal calling on the public to boycott the play as long as Melmoth was still in the cast.
Split into simpler sentences: Melmoth refused to speak the opera's epilogue, as she disapproved of its patriotic sentiments. The "New York Journal" called on the public to boycott the opera as long as Melmoth was still in the cast.