Interesting discussion y’all are having. I’m trying to visualize how I would react if my husband (Agnostic like me) came home and told me he wanted to join the Church. Perhaps my family is just different but I would support him. I would, however make it clear that it is his journey, not mine. I would have no problem discussing what he would learn in RCIA. I’d be interested in that, too.
I think that as long as you’re clear that this is YOUR journey and you place no expectations on her/him then there shouldn’t be major problems. Many minor ones you’ll have to work out will, of course, occur but like any discussion or disagreements you will face them one at a time. There might be areas where you have to give in to her wishes and areas where she has to give in to yours. Acknowledge those. Even if it makes it sound like a business negotiation.
I assume the faith of the children would be a big problem unless you decide before hand that this is one decision you will let her have. As hard as that might be for a Catholic, the marriage itself is important, too. And things may change down the road as she…hopefully…gains understanding of what Catholics really believe vs. what she thinks they believe.
Talk to your spouse. Your fears may be grounded and they may be ungrounded…you won’t know and can’t deal with it until you let her in on it! And in all discussions, remember to tell her you love her very much and know this is a hard for her.