You and he are having an 'emotional' affair by email. And if something more happened during a trip than you are encouraging the 'affair'. How is this fair to his wife? To him? and to YOU? By him not responding, he might be waiting to see if you'll 'beg' for him (controlling)..or maybe his wife has found out?! I suggest go cold turkey and back away. You have to try to break these ties because as you said you are becoming to dependent on him for emotional support or more.

Good Luck

Ocean