Seeing all these replies from people that appear to be morally off put by prenups...
A marriage as it occurs in our time is not a contract between two people, not a contract with God. It is a contract between two people and the state. If a prenup is something that is abhorrent in some way, then why is a marriage license not also abhorrent? If it's about love and trust, then why not just be "married" in your hearts, in the eyes of God, however you see it, and forego the contract entirely? I'll answer: because it is, always, about the contract.
I'm "married" like that, pair bonded, the commitment is between us, the love is as iron clad as with anyone that is legally married. But there's no contract between us and the state. It is about trust for us, we trust each other so much that we don't need that legal agreement.
Why would we? Tax benefits for one. Inheritance, structuring or property ownership, that stuff. We will enter into agreement with the state insofar as our pairing when it makes financial sense for us to do so. It will change nothing between us emotionally or as a matter of trust in one another, all of that is already eestablished between us. And when doing that, we will probably draw up that contract on our own terms rather than those of the state, what you'd call a prenup, to both our liking.
On your question, you need the advice of a lawyer, not advice from random people here, and you need to discuss between you and your wife what is fair to both of you beforehand.