Hi green:
If he bought his ticket without telling you before he did it, and you only found out afterwards: Bin him! He's using you!
If you both live together and it's your place: Bin him! He's using you!
If he's refusing to let you go as well: Bin him! He's probably cheating on you!
If you have any doubts about his fidelity: Bin him! I assume you're quite young. Make the wrong decision and you'll live to regret it for a long time to come.
Your only "mistake" would appear to be getting pregnant(unless of course it was planned?) Even if it wasn't, you have a massive decision to make regarding whether or not you will go ahead and have the child. Even if you do, which hopefully you will, your b/f will be no use to you if he's prepared to fly off to the other side of the world leaving you to literally hold the baby!
If you have any close family nearby, get and speak to them and seek their advice. It's at times like this when families are most needed.
Not every relationship works out for the best, but there's plenty more fish in the sea. Best of luck.