Ok - this is tough. You're getting a lot of good advice. The biggest piece is breathe. Stay calm, think this thru. To expose or not is tough, you certainly don't want to do it on emotions (I made that mistake...). You certainly want enough evidence because your H is going to deny, deny, deny and have these great excues lined up. You need concrete evidence IF you choose to expose. There are varying opinions out there on wether or not to expose.
As far as your H goes, his behavior seems to indicate guilt over what he is doing.
Only you can decide if an A is a deal breaker. There are many on these boards that have overcome As and many that have not.
Keep posting your thoughts, vent your emotions here, and throw your ideas out here for others to help you wicker thru.
I also personally completely agree with treating your H like an acquaintance. Nothing more than you would treat a co-worker, not a great friend co-worker, but just one that you have average/normal friendship with. Give him a taste right now of what life without you will be like. Acquaintance mode!
M39 W41 Two children WAW bomb dropped 11/7/09 Piecing Aug 10 - Nov 10 No longer piecing...Nov 10 Separation Jan 11 EA ends again Feb 11 Piecing attempt #2, Mar 11