If your plane ticket cost $400 and you cancel your trip and let it go to waste, it will be the best $400 bucks you can spend. Consider it buying a good choice, or buying your own sanity. Going will cost you a lot more than the price of the trip.
If you blocked his number, how did he call you on your birthday? or did you just DELETE his number thinking that you could handle hitting ignore when you saw those familiar digits pop up?