doobie GEL is a valuable resource. I just wanted to say EA's are probally more common than PA's. Don't borrow more thouble than there actually is.
Do the key logger and records thing. Don't feel like you are doing anything wrong. You are looking for honesty, what is really going on, when and how often.
If you find something it Still does not mean a EA, or PA or that you should go along with his interactions with a potential OW. If the records show something might be going on you have a right to have him stop this type of activity.