Lady Macbeth and Macbeth both commit the murder of King Duncan. Macbeth deals with his guilt by succumbing to his paranoia. Lady Macbeth deals with hers by retreating into her mind and entering a sleepwalking state.
When the witches tell Macbeth that he is going to be king, he tells his wife. Unfortunately, Macbeth does not get named next in line. She decides to help along the process, and comes up with a plan to murder the king so Macbeth can take his place. Macbeth is reluctant to do this, but she encourages him. Thus they are both responsible for Duncan’s death.
Macbeth feels guilty about murdering Duncan, and as a result worries that someone will find out. He suspects Banquo, and has him killed. He believes Macduff is plotting against him, and has his entire household killed (but Macduff is not there). What’s worse, he begins to believe his old friend Banquo is too much of a liability, since he was there when the witches made the original prophecy.
Our fears in Banquo
Stick deep, and in his royalty of nature
Reigns that which would be fear'd. ’Tis much he dares …(Act 3, Scene 1, p. 42)
Banquo knows too much, so Macbeth has him killed and tries to kill his son as well. He is also worried that Banquo might be a threat since the witches told him that his children will be king.
Macbeth relies more and more on the witches to tell him he is safe. They deliver strange prophecies that suggest that Macbeth is safe because no man born of woman can kill him, and he’s safe until the forest comes to him. Macbeth assumes that he will be fine, and seems to have forgotten that the first prophecies were half-truths and did not turn out as he expected.
Lady Macbeth, on the other hand, deals with her guilt by turning to madness. She retreats into her troubled mind, in a state half between waking and dreaming. During her sleepwalking stint, she constantly tries to wash the metaphorical blood from her hands.
Out, damned spot! Out, I say! One–two—
why then ’tis time to do't. Hell is murky. … Yet who would
have thought the old man to have had so much blood in(35)
him? (Act 4, scene 1, p. 77)
Lady Macbeth’s hysterics are directly related to her grief and guilt over having been so instrumental in killing Duncan. While Macbeth is the one that did the actual killing, he would never have done it if Lady Macbeth had not prompted him.
The way each Macbeth deals with the guilt is demonstrative of their personality. First of all, Macbeth is paranoid and conceited. His wife, on the other hand, is ambitious and methodical. Therefore Macbeth reacts to the murder with further paranoia and murderous actions, while Lady Macbeth loses her mind.