How is Lady Macbeth controlling?

Lady Macbeth controls her husband using a combination of shame and manipulation. She uses shame through repeated attempts to emasculate Macbeth. She questions his commitment to the murder of Duncan, calling him a "coward" (I.vii.47) for equivocating as he does. She draws on her own experience as a mother, saying that if she were to be in his position, she would be so resolute as to smash in her own child's brains (I.vii.61-66). This bastardization of the ultimate image of womanhood - being a mother - suggests that Lady Macbeth sees a reversal in the gender roles of her and her husband.
This is clearly a successful tactic and allows Lady Macbeth's manipulation to land. Her husband responds by reaffirming his commitment to their plot. His words of affirmation echo hers of manipulation from earlier in the play. He ends Act I by stating "False face must hide what false heart doth know" (I.vii.95). This is the literal interpretation of Lady Macbeth's much more eloquent subversion to "Look like the innocent flower,/But be the serpent under 't" from two scenes earlier (I.v.76-7). It is almost as though through exuding her own power over her husband, Lady Macbeth's strength, thoughts, and resolve are manifested in him.
This cycle of shame driving manipulation continues but wanes as the play progresses, with the murder of Duncan being Lady Macbeth's high point of control. Later, as Macbeth plans Banquo's murder and his subsequent assassinations in his power-hungry climb to the top, Lady Macbeth's control decreases as he becomes the primary agent. As her power and control recede, chaos and instability reign through the reign of the new king.

What you will notice about Lady Macbeth is that she is very controlling towards her husband, Macbeth. When she finds out about the witches' prophecies in a letter from Macbeth, for example, her controlling nature becomes apparent. She is determined that Macbeth will murder Duncan and immediately makes preparations for this event. These preparations include asking the spirits to "unsex" her so that she can be crueler and choosing the murder weapon. Her controlling nature, therefore, makes it impossible for Macbeth to take charge of this situation.
In addition, when Macbeth has second thoughts about killing Duncan, Lady Macbeth immediately manipulates him. She attacks his masculinity to ensure that he bends to her will. Lady Macbeth, therefore, controls Macbeth psychologically and uses humiliation to make him do as she says.