What is the psychological state of Macbeth and Lady Macbeth ?
Immediately after Duncan's murder, and even before it, Lady Macbeth is trying to maintain calm while Macbeth gives in to his anxiety and panic. He hallucinates a bloody dagger prior to the murder, aware that it is the result of his "heat-oppressed brain." After the murder, when Macbeth is falling to pieces over not being able to say "Amen," Lady Macbeth says, "These deeds must not be thought / After these ways. So, it will make us mad." In other words, what's done is done, and she wants them to move forward so that dwelling on the past doesn't drive them crazy. He feels that not even the entire ocean contains enough water to wash his hands clean.
However, later, after Macbeth has ordered the murders of Banquo and Fleance as well as Lady Macduff and her children, Lady Macbeth succumbs to her guilty conscience while Macbeth seems quite hardened to the violence for which he's responsible. Lady Macbeth sleepwalks nightly and sees Duncan's blood on her hands, dreaming that she cannot wash it off. Further, her nocturnal ramblings make it clear that she is burdened by her guilt. She asks, "The thane of Fife had a wife. Where is she now? -- What, will these hands ne'er be clean?" Ironically, she is in mental ruins because she has created a monster who orders the killing of children without remorse.