<human>: Can you give me the gist of the text in a nutshell?

I work at my university as a program assistant (basically a glorified secretary who reports directly to a faculty member).  I've known my boss for approximately two years--she was my advisor and we really grew close as friends before I began working for her.  

The beginning of our working dynamic was great, I would get stuff done and she would be complimentary and supportive.  The program continues to grow, we get into a couple of little arguments, but I figure all is well.  Finally, a disagreement occurs and she basically lays out everything I've done and how ineffectively I've done it (even things she was initially satisfied by).  

We ended up meeting with her superior to work through this, and we were making fine progress.  Now, when she asks me to do something, if I don't understand what she wants immediately and ask for clarification (or do the task to the best of my ability), she says "Thanks!", does it herself, and then follows up with me a week later asking me to do something such-and-such way instead. 

I spoke to her about this today, and asked her to just be upfront when I do something that isn't to her liking instead of taking it off my plate.  She accused me of arguing with her and escalated the conversation (and her tone of voice).

Every time I've tried to make the dynamic more comfortable she's become angry.  We used to have a great rapport and dynamic, and now I just feel like she's constantly seething at me and there isn't any room for improvement.  Either I do what she wants, and that's fine, or I fuck up and that's completely unacceptable.  

I don't know what to do.  Thank you for your feedback!
<bot>: working for someone who I was friends with before, she becomes angry with me when I don't understand what she's asking me to do and when I attempt to discuss the problem she becomes combative.