What should i do i am having problems with my friends?

So have been having some problems with my friends for a while now and i don;t know what to do? On Dec 2nd 2012 was my friend's bday party. So i was not invited because she told me so may invites were allowed funny how all my friends from church got an invite but i did not get 1 which i think she is lying because how do all of my friends get invited but i did not. 2nd problem is on Jan 2nd 2013 2 of my friends had a birthday on the same day so their was a party but i was not invited funny thing is all of my friends from church were invited but not me. I was told only so many people could get an invited which i think i was lied to get again just like the party form Dec. 2nd. Final problem is a friend was leaving to the Marines and i guess he was having a going party but this time no one bother to call text or even facebook me. So i was told my all 4 of my friends oh had a event said we r so sorry its just only so many people could get a invite or we for got to tell you that you might of had plans. I said if i had plans then i would have switch my plans around then i oculd have gone. When i go to Church Thursdays nights well my friends know that i am mad. What to do?