How to deal with a difficult co-worker?

• how does online banking work
• best work online
• define an environment
• virtual learning environment

I may be overreacting, but this is what is happening. One of my colleagues who is not even from my institution is acting as if she is my boss and trying to control me into doing work for her with no guarantee that I will be able to use this work for myself. My boss is much nicer than her but he is trying to be political all the time because he thinks she is contributing a lot to his project. I understand the latter part, but it is getting at the price of her sending me disrespectful e-mails asking me to do the work as soon as possible and Ccing him to make sure I do it. It's like she thinks I won't do the work unless she somehow involved my boss or held something else that I am doing hostage. As soon as one of my papers gets to be sent to a journal, she feels uneasy because I got what I wanted from her and she thinks I will stop working for her. The problem is that I don't really work for her but with her and she doesn't seem to see the difference. The only thing that might make her think that she is better than me is that she is older and more senior. Otherwise, I have achieved objectively a lot more than she did in very few years. I am not sure how to deal with this situation. I am very happy to have a nice boss and I don't want to screw things up just because this person is acting out. I am being very polite and objective in response to her disrespect but I am not sure if that is the best approach and whether I am encouraging bad behavior. Any advice is appreciated.

How to deal with a difficult co-worker?