Lewis, I am sorry for what you are going through and think that each time something positive happens she may act positive. In your mind that means she's making an effort, she is going to stop drinking and straighten up. In her mind it just means she is going to have a nice dinner, nothing is going to change. It's not the same at all. And of course she is not going to want to talk about it because then you will expect her to have ACTIONS behind her words and she definitely does not want that.
I certainly do not want to come off harshly, just wanting to point out the difference.
Good Luck in getting your mind to where it needs to be in all of this. One day you will realize she is not going to change her thoughts and actions so you are going to have to change yours.
Blessings.