I'm sorry to say, but I am laughing at this. I have dealt with too many difficult patients and family! Some people can be so awful! It doesn't sound like your management is helping either. I'm thankful that my management tries to resolve issues without throwing me under the bus.
I learned how to deal with difficult people in hospice. Those patients and family members are in major crisis mode. They are not always the nicest and to make matters worse, you are in their home. I think it's best to never escalate your voice to their level, acknowledge that they are facing a tough situation "being on isolation is just that, isolating. It must have been difficult to not be able to see the CNA smile". Let them vent, so they feel like you are listening. Realize that these people are facing tough issues, probably have mental health challenges and use that knowledge to NEVER take anything personally (super challenging, I know!). But still state simply "personal insults are inappropriate, please keep your comments on topic". Also, if personal insults continue tell them "I will not tolerate this behavior", and walk out if needed.
Hope this helps.