When I went to rehab we had a Family Day where spouses and close family visited. Part of it was to see their loved one, but the more important part was to explain to the loved ones how life would be different and help them understand the adjustments that may happen.
For example, recovery is a major comittment in ones life. She will probably spend a lot of time going to meetings, meeting with her sponsor, etc. Oftentimes spouses look at rehab as a place to go to get fixed. That's really not how it works, it is a life long process that can be very difficult for others to understand. She may seem to be a very different person when she comes back and she will need your support, which is not always easy. There is a lot more involved than not drinking or using drugs.
My guess is that they want to meet with you and the theripist to discuss things such as this in a neutral setting. Were she and her sponsor to meet alone with you it is easy to feel ganged up on and like you are being forced into a corner for no reason you understand. My suggestion is to be as flexable as you can, check out the Friends and Family board or perhaps Al-Anon, and live life as we addicts try to. One day at a time. Take care.