Lady Macbeth may be part of the reason for the tragedy in the play, but the play is not titled Lady Macbeth but Macbeth.
It is Macbeth who makes the decision to kill Duncan. It is Macbeth who does the actual murder. It is Macbeth who kills the grooms to cover up his murder of the king. It is Macbeth who chooses to kill Banquo who he knows suspects him or foul play, plus the prophesy that he will beget a line of kings. It is Macbeth who orders the slaughter of the Macduff family.
Lady Macbeth is only responsible for pushing her agenda. She loves her husband and feels that he was passed over by Duncan in favor of his young and untested son. Is she evil? No, not really. She has to call upon evil.
Macbeth is the tragic hero and only he is responsible for what happens. He has free will and he chooses to do what he does. Lady Macbeth just gave him a nudge in the "right" direction.
In the classical definition of Tragedy, the protagonist must be the agent of his own downfall. Though Lady Macbeth is a strong figure in the play Macbeth, she, as the title implies, is not the protagonist. At least, again, speaking classically. And by this definition, she is not responsible for the tragedy, only an accomplice to it.
Scholars, through the centuries, have had a field day creating all manner of ways of analyzing the plays of Shakespeare. However, no matter how learned the person presenting this or that argument for "meaning" in one of the plays, it remains one person's opinion. If you wish to create an argument that suggests that Lady Macbeth is responsible for the tragic events of the play, you must find adequate support in the the text.
In the links below, I have provided three scholarly interpretations of Lady Macbeth in order to demonstrate that there is no one answer to your question, only deciding upon your point of view and carefully supporting this position with references to the text.
Lady Macbeth of Shakespeare's bloody tragedy is certainly a force in the pathology of evil deeds that have generated more evil deeds. Moreover, she is responsible for the disintegration of the marriage between Macbeth and herself, propelling the tragedy of the imagination.
Renowned critic, Harold Bloom, contends that Macbeth is a visionary tragedy. Macbeth himself is an involuntary medium, frightfully open to all that is fair and foul. Lady Macbeth, initially more enterprising than her husband, falls into a psychic decline for causes that are more visionary than anything else. But, until Lady Macbeth becomes mad, she is an extremely strong force in Macbeth's life. In fact, she seems as much his mother, directing his actions, than his wife. For, Macbeth lacks any will in contrast to Lady Macbeth who is sheer will until her breakdown. And, after being almost coerced into killing Duncan, Macbeth feels much chagrin and regret:
Had I but died an hour before this chance.
I had lived a blessed time; for from this instant
There's nothing serious in mortality (2.3.95
Yet, as Lady Macbeth becomes insane, Macbeth, admits to his own "vaulting ambition," and pursues his design to remain king. He becomes, as Bloom writes, "the nothing he projects" keeping others from taking the throne. Somehow, though, this
nothingness remains a negative sublime; its grandeur merits the dignity of tragic perspectiveness. (Bloom)
Left alone, Macbeth fights vainly against the preternatural forces and is greatly defeated. Without the directives of his mother-figure, Macbeth finds all his tomorrows marching toward a vision of a dusty death, but it is a death to which he has directed himself through his belief in the supernatural world and his paranoia and ambition. Ultimately, Macbeth is responsible for the tragic consequences of his ambitions.