He is being very selfish especially when you have family so far away. This is unreasonable. I got a feeling that if this was his family he would want to go. To give an ultimatum is more unreasonable. You will make your own decision but what happens the next time he thinks strongly about something = he will threaten you with something. This is an important milestone. If you don't go you teach him that he can throw his weight around and get you to change your mind. That is not how couples handle their problems.
If this is helpful press accept