First let me say that I'm very sorry you have to be here, but I'm very glad you found us. There are a lot of people here who will give you great advice and support.
If you look in the corner of the screen you will find the Healing Library. I suggest you start reading there, as it has a ton of information.
Secondly, I would hold off on confronting your WH until you have discovered more information. Make copies of everything you have and put it in a safe place your WH can't access.
Start digging as much as you can. Keyloggers are great for computers, and if you think he is meeting the OW in your home (or his car) you can get VAR's (voice activated recorders). This will help you get more info on what exactly you are dealing with.
Good luck, this is not an easy journey, but we are here for you.
Trust is like paper. Once it's crumpled it can never be perfect again.