I can completely understand where you are coming from Claire. My family is exactly what you described!! It is very frustrating to me and I am sure it is to you too. I suppose persistence/patience will pay off for us if they start to listen though.
I have to agree with the depression thing as well. After a glutening I get depressed for about 2-3 days and then all is well again. I have never sought treatment for it, since it is only temporary. Oh, the brain fog too. Of course my DH would say that sometimes I don't need to the gluten to get that!