In communications and relationships, there are two things that have to be present: the sender and the reciever.
If you are the sender, but the reciever is broken, the message won't go through. You may have more love inside you than anyone else on the face of the earth, but if the recipient of that love is incapable of seeing it for what it is, there is nothing you can do.
You didn't cause it. You can't cure it. It isn't about you. It is about broken people who are incapable of accepting what you are giving them.
All that being said, I dread Christmas also. This year my family will be somewhere else, and I won't have to deal with what I call "the dance". I'm pretty happy about that.
I'm sorry you're having such a rough go of it. It sounds like your family has an elaborate "dance" they do around Christmas too. Everyone has their choreographed role, and everyone knows it so well that they do it without even thinking.
Maybe this Christmas you can try to sit this dance out. Maybe you can do something different to take care of YOU and let the others fend for themselves. Y'never know, it might work.