what error has led to Cassius' and titinius' deaths

Titinius, when he discovers Cassius, recalls the words of Cicero in the beginning about men construing the plot as they saw fit. He speaks to Cassius and says, "Alas, thou hast misconstrued everything" (5.3.83). This remark, meant to imply that Cassius killed himself because he was too quick to assume defeat, also is a comment on the fact that Cassius killed Caesar. It can easily be interpreted as stating that Cassius misconstrued the facts about Caesar, allowing him to convince Brutus to join the conspirators through his plots. This further implies that even the necessity of killing Caesar was misconstrued, thus giving it a literal meaning, "thou hast misconstrued everything."