I guess it may be a little different since I am a male nurse, but family can present many problems. Firstly, I would recommend being firm with the wife, she is acting inappropriately. When the patient was wet, you could ask a charge nurse, CNA to clean the patient, if unavailable reaffirm the family member you will be in his room as soon as it is possible. Next, once the wife starting emptying or doing anything that was specifically for me to do as the nurse, I would firmly ask the wife to allow me to do what she was doing, and reassure her that I have confidence in doing my job. If she did not listen my assistant manager would know right away, and one way or another the wife would have to back off.
"Something like, I am sure you are a wonderful nurse, Mrs. ......, but please allow me space and respect to do my job."