Macbeth’s statements and behavior suggest that, since Duncan’s death, he has felt?
Your question is difficult to understand. I think you've omitted a word. If you are asking how Macbeth feels after killing Duncan I can answer that.
In Shakespeare's Macbeth, Macbeth experiences a wide range of feelings after killing Duncan. Immediately after doing the deed, Macbeth cannot get himself to say "Amen" when he hears Donaldbain and Malcom concluding a prayer in the next chamber. Macbeth also hears a voice telling him that he has killed sleep. Presumably, Macbeth feels great guilt at this point.
Later, Macbeth states that Duncan is the lucky one (because he's dead). Duncan has peace, Macbeth does not. Macbeth is weary and under pressure, and is in despair.
Later still, Macbeth comes to feel that everything he has done is meaningless, that life is meaningless. After he is told that his wife is dead (a result of their killing Duncan), he gives his famous Tomorrow speech, revealing his now nihilistic state of mind.
These are three reactions Macbeth experiences after he kills Duncan. There are more, but these should get you started.