If you're still checking in, OP, last night's alarm is over with and he's ok, which was a main concern.
There seems uncertainty around his phone availability - then later on you mentioned he'd rejected the call which suggests he has availability? Something didn't add up there.
Leaving a pregnant woman alone with the kids at night in a strange country supposedly uncontactable / refusing contact is unreasonable.
But obviously something's wrong.
Different requirements in terms of how much interaction / peace and quiet is needed - these have to be sorted and set for both in a civilised way.
The behaviour you describe has been flagged by so many posters with experience of partners having affairs.
Running away / shutting down can be a sign of something else wrong - health worries, money problems, substance abuse etc.
Two children and another on the way can just be overwhelming and batteries need to recharge. Sharpen the saw.
Need for peace and quiet, solo time, parallel play, lack of need for interaction etc have also been flagged as possibly ND characteristics.
Or it can simply mean an unpleasant cold controlling personality in play.
Whatever it is - it can't go on.
Renember the three children utterly dependent on you both as a partnership.
Hope you have a safe journey home and make a game plan for the way forward.
Find out what's wrong and plan accordingly.
Set out your boundaries and needs (and listen to his, too).