I don't believe there are any scenes other than Act 5, Scene 1 that show Lady Macbeth has a guilty conscience--if that is indeed what is disturbing her. It is not entirely clear that she committed suicide, although that seems like a good probability. She dies offstage. Nothing is said to indicate how she might have killed herself. I don't believe her guilty conscience should be considered a tragic flaw. Macbeth might need a tragic flaw, although Shakespeare never seems to be overly concerned about Aristotle's precepts, as shown in the repeated violations of Aristotle's unities of time, place and action; but Macbeth's wife does not need to have one. One tragic flaw in a play ought to be sufficient. If Lady Macbeth did have any kind of tragic flaw, it would be sharing her husband's vaulting ambition. However, she is far from being a good person who has a single flaw; she is wicked, cruel, selfish, treacherous, altogether witch-like--she has plenty of flaws. One of them is beautifully expressed by her in an image which seems to be a combination of an analogy and a metaphor: "Look like th' innocent flower, / But be the serpent under 't" (1.6.76-77). No one can possibly feel sorry for her. Shakespeare seems to use her mainly to goad her husband into committing a murder which is against his conscience from the beginning. After that she has only a minor role. Shakespeare must have felt obliged to show her undoing at the very end, since she played such an important part in the plot against Duncan.
I don't think she ever really felt guilty either since she said she would even be ready to "dash out the brains" of her own child but I can see at least one moment in the play which shows she may have hesitated and shrunk from murder : this is when she acknowledged the resemblance between Duncan, the old king and her own father and affirmed she couldn't have killed him because of the strong resemblance he bore to her father. The image of the dashed brains of the imaginary (or real?) infant, therefore, stands in sharp contrast to the image of the father. After that, before the final act, she was constantly seen as hard-hearted, contemptuous, and insensitive to her husband's plight when he started to rave and rant about Banquo's ghostly presence during the banquet... The play is full of desire and detestation, "top-full of direst cruelty." A critic argued that Lady Macbeth died "because of wickedness", because of "wicked dreams" (the etymology of the word "wicked" is allied to "witch").
However, one may feel confused and think she is not utterly bad since she stirs no feeling of hatred at the end. Why not? First probably because she is still cherished by Macbeth and that even her bouts of insanity are beautified by the love he still has for her. Next, because she is still attractive sexually. I'm not sure the traditional aristotelian principles of "pity and terror" really apply here. She really isn't a good person. It's this strange mixture of desire and hatred that eventually accounts for fury and madness. In Act V, scene 1, the cup is full to the brim and so, lady Macbeth is doomed.
After rereading a few scenes in the play, the only possibility, I think, that can't be ruled out, apart from Act II, sc. 2, l. 12-13 when she suddenly likens Duncan, the old king to her own father, is Act II, sc. 2. l. 63: "but I shame to wear a heart so white." Yet, the knocking she hears makes her retire and she hastens to add: "A little water clears us of this deed: how easy is it then!" She is frigtened by the knocking, which does not necessarily mean that she is guilty. "So white"may even point to her being insensitive and impervious to Macbeth's dismal thoughts after he had committed the murder.
This helped me a ton with my assignment. I really appreciate it, thanks!