I emailed my W last night, using the message I posted above along with Puppy's suggestion to come out and ask her if she's willing to work on the marriage. No response yet, but I know what it's going to be: "I need space, time to heal, to forgive myself, to get some clarity, blah, blah, blah." So, if that indeed is her response, is it safe to assume that the affair is still going on? Yep.
Yep, indeed, and you should tell her that as well:
"I understand; thank you for your clarity. I have no other reasonable choice other than to assume that your reluctance means you are still having an affair. I will protect myself, and make my decisions accordingly."