Absolutely is. Its an act of love for yourself and your own family by protecting them from a toxic and extremely damaging person. Its an act of love towards them by showing them their behavior has major consequences and not enabling it, helping their own personal growth and that they need to do so to have a possibility of being welcomed back.

Meaningless martyrdom might make you feel like you are being a "Good Christian" but its actively making the world a worse place AND reducing the amount of good you can do in it. And if you don't want to have any nuance in your reading of the Bible, you best be following every single word of it to the letter which I doubt anyone does meaning their hard stanced black/white views on certain things are hypocritical.