Let me ask you about documenting everything. I started in the past but quit. What's the quickest way to get it done? I'll be pulling from memory and text messages for much of the dates and such.
If you are refering to the things she does and the dates, etc., then I would say the best way to keep organized would be to get one of those pocketbook calendars that you can carry around with you and pencil in the activity on the calendar date it happens. If you have any solid proof.....like any receipts, etc.....then you could keep that in a safe filing place that is not in the home or that she could not find. Those would be two separate records to maintain. I don't think it would be as difficult as it may sound in writing.
I would like to suggest that you not continue to ask her about an A or OM. You've made your suspicions known to her, so now bid your time and wait until you have some type of proof before you bring up the subject again. That's just MHO.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!