Wow, Sue ... what a hard thing to have to read. At least now you know what was going on with him. At least it seems to be over.
What should you do now? I would definitely give him his space - GAL, etc. as you said. He has to go through that mourning period (as lousy as that seems). You don't know if he wants your M. But what do you want?
It's natural to be scared. Any of us who have gone through the waiting to see if their spouse still wanted us, have been there, done that. Best thing is to continue to take care of yourself, and your D, first. I would take it day by day with your H.