Hello. I've name changed to protect identity. My dm has lived with a very controlling and ea husband (my father) for thirty years. My siblings and I have all tried to persuade her away from him and offered accommodation, financial and emotional support over the years but she won't leave him.
Recently dm and 'd'f invited my two young dc and I to stay for a few days as they live in a remote location by the coast, so it would be a bit of a holiday for us as dh needs to work so no holiday this year. Today, our last day, 'd'f decided to be rude to me, he was being patronising and when I said 'dont speak to me like that' he stomped off, while I took dc for lunch in our annexe.
I went to try to smooth it over for the sake of dm (for whom this type of thing is a regular occurrence) and df turned nasty, said he wanted nothing more to do with me, said I'd always been rude and am a malicious person, wants nothing more to do with me etc. I know that this is classic controlling and bullying behaviour, he reduced me to tears and I walked away from apologising for something he should have been apologising to me for 
Tomorrow dh is collecting me from the station but I have to wait until then...should I never speak to df again? but I want to support dm, though I doubt she'll ever leave him.