Veritas:
It sounds as if you have your mind made up already, as it should be. However, you asked for advice and you got some really great advice from the people here in the forum.
You said above that if she ever expects more from you as a spiritual head, then you will cross that bridge when you come to it. How can you be her spiritual head (you will not be in the presence of others, but she may eventually come to decide that she really *does* need you to take more of a lead in the home) when you don't believe in God? You can't fake it, she'll know. That is a distinct possibility. Why be in the middle of a marriage having to decide about this particular bridge? You should always work out in your head *before* you are married the many things that can happen, especially if you have some control over them at this point. When you are married, and a Witness, you are already in way too deep. Right now, at least, you can assay all of your options and have an out.
I think you are logically aware how *difficult* marriage is for people that are extremely compatible, much less those that have such extreme differences. The JW lifestyle is just *that* .. it's a LIFESTYLE. It doesn't involve just going to church on Sundays for two hours. It involves *every* aspect of your life, down to the food you eat. Witnesses can't eat blood puddings. It involves every medical choice you make, every hour of every day you will be living a lifestyle that is not congruent with your true beliefs, and you eventually will become resentful of giving over so much of yourself ot something you don't even believe in. Think about it. Marriage is exciting in the way you have a companion, you are in love, and you get to have sex all the time. But eventually, things become more mundane, and that is when compatibility (intellectual, emotional, cultural, and social) helps the couple get through some hard stuff. The time when the things we share in our belief system unify us. Just think about it....
I wish the best for you whatever you decide.
Country Girl