People can act very strange to say the least coming to terms with someone's impending death. Just because someone acts like they don't have sense, doesn't label them a borderline. And more so, if the daughter is clinically a borderline, that comes from trauma, and who the heck knows what kind of family dynamics were going on there. In any event, seems to me that you were the one who had the very first "real" conversations with the family, and they were unable or unwilling to hear or cope with what you had to say. Any introduction to "guess what, your mother is dying" talk needs to come from the doctor, needs to be dealt with by the social worker, and not left up to the nurse to be the first one to set everyone straight. Prior to that conversation, I would definetely defer to the charge nurse to speak with the family about a conference with the MD. Instinct kicks in and we want families to be prepared, we want to be clear on the plan of care, we want everyone to be on the same page--but as a back up when the doctor tells them about the terminal nature of the patient's condition, and a social worker can prepare the family for the events to come. Therefore, yes, they are angry at you--to be the first one to say it out loud, it seemingly makes it so (and could even be construed by some as your "fault" for labeling their mother, therefore, every nurse is going to treat their mother as a dying patient). They may not have had any earthly idea that their mother's condition was terminal, impending terminal, and were very shocked to hear it from you. It is all crazy, and a bad spot to put yourself in, but even worse for the patient, who needs peace, comfort, and pain free as opposed to the sh** storm that you unknowingly started. It could be considered beyond your scope. It could be considered a number of things. However, you do have the right to know what the complaint says, and I would not get into calling the person at the DOH that the daughter called and the like, as then it makes you look like you are attempting to get into unethical territory. I would, however, ask for a copy of the complaint. Ask what your rights are as far as answering to the complaint. Ask if the complaint goes away if unfounded. Does it get reported elsewhere? Speak with HR about same.
From here on out, document carefully, don't give medical information if the doctor has not had the opportunity to review and speak with the patient and family first, defer to adminstration if you find yourself in a sticky situation with a difficult family. That is why they get paid the big bucks.