Othello's soliloquy in the last scene of the play reveals a number of important insights into his state of mind and the events that have transpired. In the soliloquy, Othello reflects on his actions and the consequences of his jealousy and anger. He acknowledges that he has been manipulated and accuses himself of being a "fair devil" that has brought about his own downfall.
Othello's soliloquy shows that he is consumed by guilt and remorse for his actions. He realizes that he has been misled by Iago's lies and deceit and that he has wronged the innocent Desdemona. He acknowledges that his jealousy was unfounded and that he has committed a terrible wrong by killing Desdemona.
The soliloquy also reveals Othello's deep love for Desdemona. Despite his anger and jealousy, he speaks of her with reverence and remorse, describing her as a "fair devil" who has been taken from him too soon. This contrasts with his earlier language about her, in which he accused her of infidelity and used cruel and abusive language.
Finally, Othello's soliloquy reveals his sense of hopelessness and despair. He speaks of his own death as inevitable and resigns himself to the fact that he will never be able to undo the harm he has done. He expresses a desire for redemption and forgiveness, but acknowledges that this is unlikely to be granted to him.
In conclusion, Othello's soliloquy in the last scene reveals the depths of his guilt, love, and despair. It provides a powerful insight into the character of Othello and the tragic events that have unfolded in the play.