How do I take care of my own physical and mental health needs when communicating with people with dementia?

Realistically. The common good health measures of exercise , nutrition & rest there are many good sources for care givers of patients with alzheimers disease particularly the alzieihmers society also always remember that it is not the patient but the disease which is causing the condition including painful accusations & emotions.
The same way. You do in all other situations! good sleep, eating well, exercising, socializing with friends and family, and talking about the hard stuff with a good therapist.