Do I have a right to be upset about this?

I don't know, man, I just don't know.
Cry, that always works.

There's no good reason Ты should be mad anyway because I don't know the full story on how both things happened.

i wouldn't say Ты would или wouldn't have the RIGHT to be mad. but happy birthday!

Sunday is my b-day... and chances are i'll be spending alone, или with Ты guys ;_;

Yes Ты have the right to be mad.
No Ты don't have the right to be mad.
I don't know.
Eat cookie.
Hug someone.
Spray Windex.
Solves everything.

I think Ты should be upset honestly. I know I would. By the way happy birthday. I had a birthday just yesterday.

First Happy Birthday!!!
Ты have a right to your feelings. Before Ты decided to be angry at your friend, do Ты know what he was thinking? Did he know it was your birthday?
My suggestion is to talk him about what happened and how it made Ты feel. Ты may think it's obvious, but some guys are slow on picking up such things.
Remember, just getting mad will hurt Ты еще than him.