Apparently it works for some. This happened to a friend at Christmas:
Dad is religious, Mom is agnostic. Mom agreed to go to church with Dad, as a Christmas gift. Condition was that Dad not tell the kids Mom went to church because they would mock her. Of course, Dad blabbed and Mom was FURIOUS. Awkward times were had by all ?

That sounds fine if you're describing it accurately and she is giving you the same respect and support and understanding (or at least not being an asshat).

There's no atheist holy book that commands you to cast a believing wife out until she comes to her senses. There's not even any rational basis to be authoritarian or controlling around her beliefs. I was married for years to an evangelical woman after my deconversion and it went just fine. I have zero complaints. The challenges in our relationship were minor and unrelated to differing beliefs. But both of us were willing to give each other the space we needed to think our own thoughts.

I am assuming that you are an A-theist. Why would you "be supportive" in her nonsensical belief system?

It may work and it may not. All depends on the people themselves.

Clear communication about expectations is the key, and you seem to have that covered. If she is a theist you'd need to know if she intends to try to convert you over time. You'd need to be clear as to whether or not that's something you'd accept. You'd also need to know that she is willing to accept you as you are.
Finally, you need to be sure that you can deal with church attendance even though what is taught is very likely antithetical to your own values and beliefs.

I wish you well.