The soliloquy comes in Act 5, Scene 2, after Othello has murdered his wife, Desdemona. Othello was led to believe that Desdemona was having an affair by his trusted lieutenant, Iago.
Now — how dost thou look now? O ill-starr'd wench!
Pale as thy smock! when we shall meet at compt,
This look of thine will hurl my soul from heaven,
And fiends will snatch at it.
Othello, Act 5, Scene 2