Getting rid of the alcohol in the house is just one minor thing - more alcohol is always just a short drive away! If she really wants to change, she needs to make some changes and get some help in some form. Willpower alone won't do that. I think everyone on here would attest to that!!! We've all tried that route.
I am concerned about her response to your email, sounds like she is just trying to appease you. She will quit drinking "for you" - which means if she does succeed in "white knuckling" it for a while, she will blame you for making her quit and "suffering". Been there!
Keep us posted. I've been thinking about you the last few days. I see a lot of myself in her actions as you have described them. I have felt the pain she must be in, active alcoholism is a lonely, shameful and destructive way to live. But she needs to realize that and get on board with making the changes she needs.
I'm also concerned about you getting too caught up in this. Please make sure you have some outside support (like SR!) and keep your perspective. It's way too easy to get caught up in the drama and lose yourself. Take care!