The Crazy wife and the plan

Macbeth totally wants to kill the king, but feels skeptical about it. His wife really wants to be queen and is scared her husband is to go to steal the throne by murder. She called him a coward ! He isn't a coward he is trying to be noble and do the right thing! 

Lady Macbeth is crazier then anyone in my opinion. She called on the evil spirits to rid her of her femine  weaknesses so she won't feel guilt. They planed to get the guards drunk so there not aware of what's going on and kill the king. but what if the guards don't want to drink that much? What will they do then ?