1. Do NOT tip your hand. This is the first rule. It's so tempting to flounce off to a lawyer and announce it to your cheater, expecting that boy, they'll see you really mean it this time! And half expecting them to do some Hail Mary maneuver to win you back. Bad move. When you tell your cheater that you're seeing a lawyer, all this does is kick them into high gear to hide the evidence, screw you over financially and get to the biggest pit bull attorney in town first before you do. They're probably doing that at the very same time they are trying to throw you off the trail with "remorse" and "needing time" and booking trips to the marriage counselor. Hide the payment to the attorney as well, by whatever means necessary.