I know that you are venting and probably not looking for advice, but if you will allow me to offer a few suggestions:
So many of us have been in your position. It is SO frustrating! If you feel up to it, try to change the culture of your workplace. Most of the time, people with attitudes feel "victimized" somehow. Rational people with a clear understanding of their job duties don't react with an attitude when asked to do something, do they? So why is this person being irrational? Does she feel unappreciated? Does she feel like she has too large of a workload? Is her personal life in shambles? (and the reason I ask the last question is because sometimes when employees don't have a balanced/stable home life, they act out at work-not that this is OK, but it may help you to understand their behavior.)
I had this same challenge with a particular staff member for almost two years. I finally asked her, "Mary, it is clear to me that you are angry because you reacted to my request to help Ms. X up to the bathroom by rolling your eyes and sighing. Can you tell me why you are mad?" Mary replies, "Why do you think I am mad? I just have to do EVERYTHING while you just sit around and play on the computer!" I state, "It may look that way, but I am charting, and it takes a while to get through all of it. You said that you have to do EVERYTHING, and I don't want you to feel that way. I do want you to understand that you are a valuable team member on this unit. We need you and rely on you. Do you feel that your tasks are too numerous? What can I do to help you?"
She finally opened up to me and said that she was taking care of her dying mother by herself while her 3 sisters came up with one excuse after another regarding why they can't help her, trying to keep her daughter out of trouble, and trying to keep up with her pre-nursing classes at the community college. I had no idea. She felt under appreciated at home and carried those feelings over to work; hence the comment "I have to do EVERYTHING". She was simply at the end of her rope.
To change the culture of a work environment is difficult, no doubt. But you can do it. In collaboration with your NM, compile a list of duties in a checklist form for the CNAs on your unit. Involve them as well so they feel like they have a voice in their job duties. Staff members are more compliant when they have some sense of ownership in defining their duties. Expectations are then clear cut. Try to open up those lines of communication and do small things to make her feel appreciated. A candybar, a coffee, an email to the NM pointing out the things she did well during a shift...it's the small things that make people feel good. However, if the CNA continues to have an attitude after your efforts to communicate, then she should be written up for disruptive behavior. You have to document each occurrence as it happens.
I hope this helps. I know it's frustrating, and not very pleasant. View yourself as a leader in this instance and reach out to her. You might be surprised at how her attitude turns around.