As much as you would like to explode at her, breathe and count to 10. No matter what you say, she will be that much more determined to continue to do what she's doing. The best thing would be to document what you have found and keep it close because you may need the evidence at a later date.
Right now, you are in the early stages of gathering financial info and you just never know, it might be something that can be addressed when discussing the financial data during mediation. I know it's difficult, but you've got to keep what you have found to yourself for now. The time will come when you will have your say...but get through the financial stuff first.
Just my two cents.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
