Chiachick.......

It must be incredibly draining on you as well; sounds like your situation, you might as well be talking to a brick wall.
I am a psych nurse, I have have several PTSD "upsets", however, I do not use them to cover for every thing that happens in life. As a psych Intern, I would think that she should know better....but I have met ppl who hide behind trauma as an "excuse" for everything wrong in their life & I realize there's times when I want to slap them in the face & yell "WAKE UP!" However, quite inappropriate action.......I think if you tried to gently ask her "why?" is it always her "trauma". Get her to own up w/ her current actions. I am glad that she is your friend b/c I realize how important, yet fragile, friendships can be. If it really bothers you, try to keep asking the "Why??"
Or, you can sit back & let it scrape on your nerves until it negatively affects your friendship..........ball's in your court, Chiachick..........*hug* DAYZEE9