Heyy!!
First of all congratulations to your boyfriend and I wish him all the best!!
Maintaining a long-distance relationship can be tough but it is not impossible, you should remind yourself every now and then that he has gone there to achieve his dreams, to fulfill his goals, and to have a secure future and that you are happy for him. You just need to make some efforts!!! Try and communicate with him regularly and creatively!

Also, it is important that you control your expectations. Make some rules for your expectations. You should understand the fact that he is there to make a career, he cannot be into you 24*7. He has a personal life there and similarly, you have a life here. It is very important for you to make some ground rules for your expectations.