I'm not sure I have a great answer for you. I've done detox in-patient, but not a rehab program. What I know from doing AA and NA, is that it often becomes present all throughout people's lives. It can resemble a 'cult' sometimes. But that's actually part of why it can be so effective. Regardless, getting clean and a person motivated to preserve and sustain their sobriety will often also mean major changes throughout their life. That's a natural part of the process - things changing. But as time goes on, if you feel like there are specific things troubling you, please feel free to reach out here. Also, there are support groups for friends and family of people who struggle with addiction, and I highly recommend that for you.
What was her drug of choice?
I do think you are smart to realize that it is sometimes hard returning home. Hard on them. Hard on you. Because there are a lot of old patterns still there. If one uses doc as a way to numb out and they don't have it? Then they have to DEAL with everything. My biggest advice is to get therapy as a couple. It can do wonders to help you through this.