What does this quote from Act V Sc III suggest about illusion or disillusionment in Macbeth and people in general?
I have liv'd long enough: my way of life
Is fall'n into the sear, the yellow leaf;
And that which should accompany old age,
As honour, love, obedience, troops of friends,
I must not look to have; but, in their stead,
Curses, not loud but deep, mouth-honour, breath,
Which the poor heart would fain deny, and dare not. (act V, scene III)
In Shakespeare's day, evil and the representation of it
was not governed by mere vague and irrational forces; it was peopled and controlled by the malignant wills of intelligences—evil spirits, devils, demons, Satan—who had the ability to project their power into the workings of nature and to influence the human spirit.
The quote in the question is in fact from Sc iii not v but is working towards the conclusion and Macbeth's demise. Macbeth is a little annoyed and even irritated that perhaps his own servants do not have the same confidence in him as he in himself:
Thou lily-liver'd boy. (V iii 14)
Macbeth is confident in 'his' castle and feels he is invincible due to the witches prophesies. He is however beginning to feel unease as things are proving more difficult than he expected, his wife is ill and he is having to fight for what was forseen as his. Hence was his need to kill Macduffs family just in case.
.. This push
Will cheer me ever, or disseat me now. (V.iii.20)
Macbeth is becoming so obsessed with his 'destiny' of being king that even talk of his wife should not distract him now. The illusion that his rightful place is as king is still strong and his belief in his immortality intact:
he cannot be harmed by anyone born of a woman
However, he is fooling himself and whilst relying on his own interpretation of the witches' prophesies,
The heart I bear
Shall never sag with doubt nor shake with fear" (V.iii.10)
these constant reassurances do support the view that he is becoming more uneasy.
It is only later that the disillusionment will become so apparent and his weariness too great as to contribute to his downfall.
Refer to the eNotes guides to help you get a better understanding of the phases of Macbeth's obsession.