Macbeth Act 5

Even though I do feel bad for Lady Macbeth, I believe that this was already coming for her. Prior to act 5 she did not give a care in the world as to what has happened to any of these people. She was a selfish woman. I do understand, doing whatever one wants to get what they want out of life, but there also comes a cost with that. In the beginning of act 5, the reader sees Lady Macbeth having a  struggle with herself. Perhaps everything she has done has caught up with her. She now feels guilty when it is too late. Why is it now that she seems to be remorseful?  Why did she not think about all the options when she was telling her husband to do these foul things from the very beginning? She did it just for power and look at where she has ended up. It was all for nothing ultimately. She has driven herself so mad that she feels like she has to kill herself.