Did anyone really expect Andrea to kill the Governor while he was sleeping?!? First, it is cold blooded murder and while I understand that it is the zombie apocalypse, she hasn't killed a human to date. Has she? That is a big line to cross - regardless of the circumstances and forget the fact that she has (or had) feelings for him. Second, if she had killed him, how would she explain it to everyone, especially his lieutenants? They would have either killed her or locked her up. Unfortunately, she is in a difficult spot right now. I believe her eyes have been opened to the Governor's lies (finally) - especially with what Michonne told her about the Governor sending Merle after her to kill her. Now she has to bid her time and wait for the right moment to strike. She is probably going to need help (in the form of Tyrese and his group? and Milton?). Although if she confides in Milton, then he will probably betray her and then things will get really bad for her, which is probably what will end up happening.
There are 5 eps left and I think we will see Andrea begin to try and rally the Woodsbury town people against the Governor. We will just have to watch to see what she does and how successful she is in doing it.