Welcome, mckmad. I was digging up older posts and found yours...must have slipped through the holiday cracks.
I am glad you found us, although not for the reasons why. But this is a great place to learn and gain strength to better handle life with addicts.
My first thought about your question of how to handle the rehab visit is to be honest. You don't have to play any particular role... good wife, bad wife...just be your authentic self. Be respectful, considerate and honest.
Yes, he is there for his addiction, first and foremost. But relationships...even those in ruins...also play a big role in recovery, hence even being asked to join him on this journey. You know you don't even need to go if you are not comfortable. It is your choice.
Do you go to Al-Anon? Might be a good place to start your own recovery journey.
Keep posting and reading and keep coming back. Don't let our oversight of your post discourage you...I blame summer brain...I am only half plugged in these days!
Take good care,
T