I can "hear" the anguish I your post. The anxiety. The fear. The desperation. I have felt those feelings too. And I'm so sorry that you are having to deal with the shrapnel of addiction.
I divorced my XAH. He didn't want help. He didn't think he needed it. 30 years later....he is still addicted, angry, and blames the world for his problems. Divorce was the right thing for me to do in my case. Your wife is getting help......and that's a really good thing. My son is the current addict in my life and I don't want to "divorce" him but I will distance myself from him if he is in active addiction....to the point of no contact if necessary. But today...he is in recovery.....and I reside in today.
Your question here is "What should I expect?"
Nothing. No matter what your expectations are, she will do something that will not meet them which will result in disappointment and anger for both of you. I thought people were nuts when they told me to let go of my expectations.....how the heck does one DO that? It seemed.....well.....impossible. But it's not.
Expectations are often created by imagining how things are going to "be" or should be (in our opinion) or how others tell us things "should be". We picture all of this inside of our heads and create scenarios.....that is the birth of expectations. And then if things don't play out in this preconceived way......resentment sets in. This is the essence of "future tripping".....and most people do it. It is not accepting what is "now".....this moment......today.
Instead of focusing on what to expect.....perhaps you might consider focusing on what your boundaries are. Focus on changing the manner in which you react. Focus on you.
Once I got that concept.....and changed that which I do control (me)......and stopped the expectations and replaced them with boundaries.....things improved for me and also for most of the people around me too! (Not just the addict!)
There are so many behaviors associated with addiction. It is unreasonable to expect someone to go through a 28 day "spin dry" and POOF they are the perfect person we wanted them to be. It takes a WHOLE lot of work to change behaviors....and time....a whole lot more than 28 days. That's just the beginning.
Personally, I have embraced the concept of working the program that I wish he would. It helps me stay focused on me and my own emotional, physical, and spiritual health. If I stand back and hope (or expect) someone else to change without implementing serious changes in my OWN behaviors.....eventually.....things will lapse back into what they were.....
I don't know if anything I've written is helpful to you. It is simply some of the things that have been useful to me but it took a long time and lots of missteps along the way. You and your wife will be in my prayers.
gentle hugs
ke