Why does my friend do this? -_- I'm actually annoyed?

[Im a big fat, KITTEH KAT!]

Alright, so there's a friend of mine that I am indeed pretty close to. She doesn't get out much, and doesn't have that many close friends- because she doesn't put herself out there.
The other day: me, her, and a couple other of our friends decided we'd go out to eat, then to a movie.
The original place was olive garden. We decided on a time, and sent it to everyone, but my friend however wouldnt answer her phone. Around 30 mins later, another friend (that was going with us) suggested to go to CiCi's pizza, thats right next to the theatre- as it was cheaper.
Literally 30 seconds after I got this message, My friend texted back saying she was looking for her money for the dinner and movie.
So I told her "we decided we'd go to CiCi's then a movie, cool with you?"
Then she went off, on how she's the last to know everything. How she never gets invited everywhere.
How she "Sits on facebook, looking at everything everyone else gets invited to do, and she sits here crying behind the screen" <---Her exact words (but changed I into She.) She then told us to go and to have fun (which we didn't go).
Everytime I do something with my friends she says something to me about it. And in this case, It really pissed me off.
She said she could have let her know before we decided, SHE NEVER FUCKING RESPONDED BEFORE THE IDEA WAS SUGGESTED.
-_- Sorry, she just fucking pisses me off. Why does she do this shit?

[Toughaunt849]

Because she has issues. First of all: Who in the hell sits on Facebook looking at Everything everyone else gets invited too?? She sound very lame. Let her know for now on: We're not gonna tolerate you "Trippin" for No reason over petty stuff. Or say: I don't know about you but I have my period once a month: You must be on your Everyday We still cool right?? For now on: I'll send you a text 20minutes in advance b4 we start hanging out, Is that cool??