If she asks you why you didn't warn her (or accuses you of not warning her), tell her that you are following the advice of your attorney on these matters. That this is all new to you, you didn't expect to find yourself in this position, and that you really trust him/her to handle these kinds of things and look out for your interests. Validate that you know it's upsetting to her, but that you're only trying to do what's best for the kids and yourself, considering the circumstances.
The legal system moves slowly. Your wife will have plenty of time and opportunity to protect herself, and rightfully so.
