My H is peeling crawfish across the kitchen from me so I can't get into much depth here. Just thinking about you...
You have worked hard on GAL (right?) for quite a while and established you are the better option.
That he is so intent upon hiding his actions and is physically affected by the threat of discovery (could he like the adrenaline rush?) indicates he feels the best option is to stay married to you.
However, at this point, with no lines drawn in the sand, maybe he doesn't feel the need to consider the better option?
L, you've put so much into this battle. We are here to support your choices -- not tell you like all of our well meaning friends and family that you need to "kick him to the curb". Let's work on getting your ducks in a row and keeping you out of the loony bin.
I forget, weren't you considering substitute teaching? That'd give you time to do your ebay, crafts and home improvement projects and some xtra cash to justify them. It'd also make you feel a great sense of accomplishment. Think about how all of that might weigh out against worrying about getting less spousal support if it ever even came to that.