Hi Sun,
Saying no is when my problems started! And, as others have pointed out, saying no unleashes a whole host of N wrath on the head of the person saying it. For me, it was a death/birth experience - I suppose literally in having the baby they all wanted me to abort, but also it was the start of the death of the ever smiling, Stepford wife type doormat I was and the birth of someone who slowly got better and better at speaking her mind, standing up for herself, setting some boundaries and re-claiming her life.
I'm sorry to hear of the situation you're in. It's tough, especially when your heart is in being supportive but it means having to be part of a family that can cause you so much pain. But you are right, even the most acute situations fail to illustrate their dysfunctional behaviour to them. My mum and step-dad have six children between them. Only one speaks to both of them. I did point out to my mum once that, if five of my kids wanted nothing to do with me I might start thinking it was me who had the problem not them. She responded with another false allegation to the doctors about my son.
Keep focusing on keeping you healthy. Keep saying no. Keep taking time and space for you.
((((((((((((((((((((((((Sun)))))))))))))))))))))))))))))))))))