What a story!
Your husband didn't bother to look at his statement for almost 2 months? The charge should have shown up days after you made that purchase.
Did he know you used your father's CC to purchase the tickets? If he didn't, I think it's a communication problem. He thought he paid for the tickets.
At this point, not much you can do. Why were you disputing with Amex instead of contacting Vayama at that time to deal with it?