The atmosphere in Act 5, Scene 1 is one of panic and impending doom. The scene is very suspenseful.
Macbeth has situated himself as king, by killing the king, and now he is trying to hold on to that title. However, Macduff wants revenge, and Malcolm wants to take what is rightfully his.
Macbeth is desperate in Act 5, Scene 3. He is beginning to wonder if things will go his way. He has been confident that he cannot be harmed, but he is getting unsettling reports and beginning to get nervous.
Macbeth seems to be losing it. When the scene opens, he is ranting about how he is invincible and he does not want any more bad news.
Bring me no more reports; let them fly all!
Till Birnam Wood remove to Dunsinane
I cannot taint with fear. (Act 5, Scene 3, p. 80)
He simply will not listen. He is irrational, and does not want to hear the truth that his men are deserting him in droves and ten thousand soldiers are headed his way.
Even though he says he can’t be hurt until the wood comes to him, and no man born of a woman can kill him, he seems to be getting nervous.
I'll fight, ’til from my bones my flesh be hack'd.
Give me my armor. (Act 5, Scene 3, p. 80)
He calls Malcolm a “boy” but clearly he is worried about his army. He finds out that his wife is ailing, and poetically asks the doctor to:
Pluck from the memory a rooted sorrow,
Raze out the written troubles of the brain,
And with some sweet oblivious antidote
(Act 5, Scene 3, p. 82)
Poetic, yes. Medically viable, no. Macbeth has lost all sense. He knows the end is near, and he seems to be both in denial and preparing to meet it.
By this time, a lot is already happening. Malcolm and Macduff are marching toward him. Lady Macbeth has fallen ill. Macbeth is beginning to feel his mortality.