I think the first question - armed with the information you now have - is if you feel your H and your M are worth fighting for.
Only you can decide that.
What are your non-negotiable, core beliefs? What can you deal with in a M? What CAN'T you deal with?
Sit with this new information for a day or two. Post here. I don't think I would send an e-mail, and I most certainly wouldn't let H know what all you know.
M: 40 H: 44 Married 14 years S11 & D6; D20 & D19 from previous M 2BDs/PAs, 8 years apart Piecing: April 2014