He is not in a MLC, imho...this man has always acted this way, based on your posts. Stay in the marriage while you act as if everything is fine(ish). Let him do whatever he wants to do, which he will do anyway.
I think of this like Katie Holmes and Tom Cruise like....tell only the people you need to, no friends, just those that need to know.
Get a plan together that allows you to stock money, search for a place near your mom, plan for the future without him which will be 7-9 months after baby is born, know your rights(as karma says) and protect your self physically and financially. While you are doing this you can observe him and see what happens and continue your current GAL plan. That may be enough for you take on at this point...only you can tell.
