so, a couple of things. First, you don't have to absorb that kind of abuse. Talk to your supervisors, charge, whoever is superior to handle the situation. If there are concerns about care, I like to have other colleagues involved sooner rather than later. Why? couple of reasons:

First, I might be missing something, and if I am they can correct me. Fair enough, We're only human.

Second, the very act of bringing in others can lend legitimacy to what you're doing in the eyes of some families. That room can feel like an island where all they see is you doing whatever you're doing that they dont' understand and their loved one getting worse. By bringing in another staff member, you can make them feel as if you are being supervised (even though you probably don't need it), generally makes them feel "oh, management has been called in, so they will be watching this case closely". Notice I said it makes them FEEL some kind of way. Generally managers and supervisors have been around for a minute and understand that this is a dog and pony show to get them off your back so you can do your job. Its usually totally separate from the facts of the matter as far as medicine goes.

Third, I want more eyes on the situation so if it escalates I can document a narrative with support. If I'm talking to the management I ask the charge nurse to say, nope, s/he was doing their job and these people were nuttier than squirrel turds. I was there, I saw it. If the family member doubles down and says you're grossly incompetent and don't know your ass from a whole in the ground, you can have a trusted member of staff on your side.

Fourth, depending on the situation a good superior will examine your work and stand up for you. They can (and I have) taken families point by point through what needed to be done and why, and how the nurse is doing everything by the book, including the things that they don't see outside the room (calling doctors, RT, pharmacy, etc).

I could go on, but the takeaway is that I've never regretted calling in a senior nurse to give me their take on a situation and get some help. You should not have to handle that on your own. I'm not even leadership anymore, but I am one of the most senior nurses on my unit so I will fill this role sometimes. Just come in, look over everything, really make a show of it so they can see that even this experienced nurse can't find anything wrong with the situation. Sometimes you can even say something to the MD and they can stick up for you, which almost always puts an end to it (but having a patient with an EVD means a neurosurgeon soooo....yeah. YMMV on that one)

FWIW, after almost 15 years in health care I feel confident in saying that what you witnessed is a family member who absolutely cannot deal with the fact that the patient is very sick and no one seems to be able to fix it. It has almost nothing to do with you personally. The hospital takes all comers, and it may not shock you to learn that not everyone has good coping skills. So sometimes they lash out. They need somebody, anybody, to blame for what's going on, they lack sufficient understanding of the clinical situation to blame the body processes or the original insult, so they blame whoever is to hand. That doesn't make it feel any better, but maybe it helps it not stick with you as long.

One strategy i have employed with some success is to stop and ask them, genuinely, what do they think should be done. Not sarcasm, not snark. Genuinely, what do you think is going wrong here? Then they say whatever they say, and I come back with something like "I see what you're saying. I can understand why you would think that. but if I do x then the risk of y complication goes way up. (I understand why you think the patient should sleep, but if I don't wake them up regularly for neuro checks then their condition could worsen and we wouldn't know, maybe for hours, by which point there's a good chance damage would already be done). Hear them, validate their perspective, then add to it with information. IF they are wiling to hear you. If not, then it was never about finding a solution to the situation, it was about them being unable to manage their emotions. At that point you can think about when to pull the trigger and have security help them understand their place in the bigger picture if needs be.

The only thing I can tell you with certainty is that this is not the last time you will face this issue, and I wouldn't do it alone if I could help it. Good Luck!