Complex sentence: Angered over this perceived betrayal, López began fantasizing about how he could inflict pain on the singer and began plotting "a deliciously sadistic plan" to "punish" Björk.
Split into simpler sentences: Angered over this perceived betrayal, López began fantasizing about how he could inflict pain on the singer. He then began plotting "a deliciously sadistic plan" to "punish" Björk.