You really don't have to put up with this abusive behavior unless you choose to. It may be time to confront the reality of these relationships, and not expose your own children to controlling and abusive behavior of these lunatics. Of course, it does let them know exactly who these people are!

Sounds to me like it's time to draw the line in the sand and stay on your own side. Define your own "holiday tradition" and stick to it! You may have a few of these relatives ticked off with you, but so what? They have no respect for you anyway.