Complex sentence: While confronting his tormenter, Arnie expresses his sincerest apologies to Dave for bullying him all his life and asserts that Dave didn't deserve the abuse, but he laughs when Dave reminds him of the kiss incident and Dave attacks back.
Split into simpler sentences: While confronting his tormenter, Arnie expresses his sincerest apologies to Dave for bullying him all his life and asserts that Dave didn't deserve the abuse. But Arnie laughs when Dave reminds him of the kiss incident and Dave attacks back.