In "Othello", jealousy is what appears to destroy him. Othello takes the word of an alleged trusted man, that his new bride has deceived him. Betrayal and manipulation lie at the heart of Othello and the jealousy destroys them all.
This powerful destructive emotion was first suggested by Othello's trusted friend "Iago the Honest" when he says, "O beware jealousy; / It is the green ey'd monster, which doth mock / That meat it feeds on" (III.3, 169-170). It was Iago's own jealousy that put the wheels in motion for Othello's demise. Iago was angered at Othello for passing him up for a promotion of Lieutenant. This title was give to Cassio, for this Iago set out to destroy them all.
Iago saw how easy it was to manipulate Othello in to believing that his wife Desdemona has betrayed him with his Lieutenant Cassio.
Because of Othello's insecurities and tendency to overreact, this made Iago's plan go smoothly. Everyone fell prey to Iago's game, but even Iago did not expect it to go as far as it did.
This obsession has Othello's mind so set on one idea, he will not hear of any other explanation to sway him. This is evident when Othello sets up Desdemona with her missing handkerchief "I have a salt and sorry rheum offends me. Lend me thy Handkerchief." (III 5 46-47) No matter what Desdemona said, Othello would never be persuaded that she lost her handkerchief.
Until the moment Othello kills Desdemona in a jealous rage he sees nothing but this madness that has over taken him. When Othello finally realizes he killed his beloved Desdemona mistakenly, he recovers. Othello is saddened beyond repair and takes full responsibility for her death and calmly takes...