oh ew, i can't beleive i'm resorting to relationships.

so i've been "friends" with this girl since 1st grade, obviously we've been through the ups and down BS. i know friends usually die off. lately this girl has just been...different. to keep the story short, everything about her has changed. she's being a little hypocritical and all she does is talk to this girl when 3 months ago she was all up in her face saying we hate her [which we honestly do, the girl doesn't get the point that she annoys us, you'd think there would be a point after 2.5 years].
OK. enough of that...
the real point.
i can honestly say i'm a bitchy person about a lot of things, i know when i'm annoying, i know when i say/do stupid things, i'm just overall aware of my actions. this "friend" does the same things as me [the hypocritical part], gets onto me for it, says i need to grow up and stop being so bitchy and stuff. she's the type of person to assume so much crap.
so i wrote her an extremely friendly little note about a week ago explaining myself and simply saying she does the same thing. notice i specifically stated in it that i was NOT looking for drama-i said either ignore me and stop the crap, or talk to me and forget it all. she came back at me with this extremely immature thing, of course being hypocrtical, turning things around, taking things beyond what they mean, and just plain being immature.
i did what i thought i should do at the time, considering i said i wasn't going to start anything-i wrote her this insanely short two-sentence letter. it once again stated i don't want drama and i had a little respect left for her before that. i think it was the right thing-i'm one of the very few people to think before i speak/act.
THE REAL POINT...i swear this is it. she started just randomly talking to me yesterday being friendly which i was like "ok this could work" and such. but i find it strange that the note is still bothering me. i'm not one to let things go easily, but i can usually just push it away until it doesn't effect me as much.
what should i seriously do from this point? i'm obviously just going to go with it and talk to her, but that note was just so immature i can't drop it.

[edit-that was so much longer than i wanted it to be. also, the word friends is in quotation marks because i rarely refer to people as friends.]