Nata....I think that, in an ideal world, it is best if the adults in a child's life can proceed with civility and respect for each other. After all, this is where the developing child learns the first...and, maybe the most lasting lessons about how people should be in relationships....
Of course, I realize that alcoholism, abuse, and many mental disorders can make this very, very difficult to do....and warp some situations....
If you can carry off the Christmas dinner....I see that as a good thing...at least for your son....