Final answer:
The line "She should have died hereafter" is spoken by Macbeth in Act 5, Scene 5, reflecting his despair over Lady Macbeth's death and the futility of life.
Step-by-step explanation:
The line "She should have died hereafter" is said by Macbeth in Act 5, Scene 5 of Shakespeare's play. This moment occurs as Macbeth reflects on the news of his wife's death and the futility of life. The phrase speaks to Macbeth's despair and his sense that Lady Macbeth's death was inevitable, implying that it might as well have occurred at a more opportune time, given the chaos that surrounds him.