See if you can find a local monastery at which to observe all the liturgies of the Octave of Christmas. I think you’ll feel very refreshed from a place where the exteriors match the interior you’re hoping for. The need to flee from the excesses of “the world” is an old one, after all, and it is why monasteries were founded in the first place.
As for everyone else, leave them to their exteriors and the interior meaning they have for them. No need to judge them. It will only keep you from feeling serene yourself. Those who have “hijacked” the holiday, after all, are expressing a thirst. You can’t blame someone for what they do when they have a thirst that they don’t realize how to quench. Figure that they’re trying their best, and if they are trying to be charitable towards others, well, in Heaven’s eyes that is a point in their favor. Not easy to do, but don’t be hard on yourself, either!
As for everyone else trying to talk you out of a healthy response to an toxic family, remind them that forgiveness is something one side can accomplish, because it means that you bear no ill will against those who have offended against you, which you don’t, so you’re good there. Reconciliation, unfortunately, takes two sides, which is why we have a Sacrament of Reconciliation. As it is, you are a near occasion of sin for your family, so you are leaving them alone. These others may not understand it, but they need to refrain from talking you out of it. Repeat. Repeat. Repeat. It is an educational campaign worth doing, even as much as it costs you to do it. Someday, you may save someone who has been beating their head against an impossible situation from continuing to try to change what is not theirs to change. You may be the person who causes them to ask, “Do you mean I can both love my family and deny them access to abuse me?” Major revelation, right? Freeing that one person will help the hassles from everyone else be more worth having to endure.
As for your relatives who tempt others to rash judgment, it is verse 3 of the same song. Hang in there. Love covers a multitude of sins. Continue to put in the loving distance you’ve put in, and your will have done the kind of sacrifice that pleases God and covers sins.