Maybe the letter upset him. I think they want him to go home and appoint Cassio governor in is place
Is he angry?
Marry her? That whore? Please give a little credit! I'm not stupid Ha Ha!
He's laughing already!
So now I'll ask Cassio about Bianca , she says you're going to marry her, are you?
You believe your wife would cheat on you my husband begged me to get that handkerchief and give it to him Desdemona would never give anyone that handkerchief to anyone!!!!!!!! Oh ,my mistress.
Here Othello strikes her afterwards because she starts defending Cassio which makes Othello angrier. And including makes Othello think she is not afraid or embarrassed the fact the "She cheating on Othello" and Othello is shocked.
In this scene Iago is manipulating Othello that Cassio is talking about Desdemona but actually talking about Bianca the prostitute.
here emilia get s the courage to tells the truths to Othello that her husband has been lying about Desdemona cheating on her and tells her about the mistake to made about giving her husband the handkerchief.