"best" friend

So, I consider Becca my best friend, 'cause she's the only friend I ever hang out with.

I'm ticked off at Becca.
She does these things that just irk me.
She is intensely selfish, like, to the point where I'm afraid to ask for a sip of her soda.
I don't know what to do, these habits she has are so completely ingrained in who she is SHE doesn't even notice them.
Nothing phases her, but everything does. She parades around like the queen of the world, but is totally self-conscious.
I can't stand her half the time, but I'm too scared I won't have a friend if I do, I don't say anything.
What do you do when the only friend you really have is a selfish, bitch who never wants to do anything, but gossip, eat and talk about things you have zero interest in?

I guess, you just leave it alone.