what should i do

How did YOU find out his engagement/wedding?

If you found out this information from his room mates..........then his room mates can get into trouble.

This guy is NOT obligated to tell you about his engagement/wedding.

How does his engagement/wedding affect your life? You friend didn't tell you about this khabar..........kya aisa karne se tumhari zindagi khatam hojaye gi? Kya tumhay koi nuqsaan hoga?

Maybe your friend did not want to tell that many people about his future plans. Maybe he had his own personal reasons for why he did not share this information with you. That doesn't mean that he doesn't like you as a friend. It simply means he's a private and reserved person.

Think about this........if his engagement/wedding is not going to affect your life, then just let it go and move on. You can also congratulate him after he gets married.