Macbeth cannot decide whether he wants to commit the murder or not. On the one hand he likes the idea of being the King and on the other hand he doesn't want to do the evil act of murder and knows that it would be very wrong. He is worried about how murder would mean he would go to hell.
Eventually when the King goes to Macbeths castle for dinner Macbeth who is still in doubt gets pressured by his wife and gives in to the temptation and persuasion of his wife. Macbeth murders the King at night after Lady Macbeth got the Kings guards drunk.
As soon as Macbeth has committed the crime he feels the almost unbearable guilt of what he has done. Macbeth deeply regrets what he has done. His wife says how she would have done it herself if the King hadn't resembled her own father. I think that this was just an excuse for not wanting to do it herself.
Macbeth gradually gets deeper and deeper into the hole he has made for himself. Things get worse and worse and end up in death for Macbeth.
A good question about Macbeth is who is more evil, Macbeth or Lady Macbeth. There are arguments for both. Macbeth is the one who actually commits the murder but the question is would he have done if not for the influence of his wife.
I think that Lady Macbeth is more evil than Macbeth because it was her idea in the first place to commit the murder and I think that Macbeth is just a good man that got pushed and tempted into a bad thing. I think that Macbeth was a man who dug himself a whole and couldn't get out.