A boundary isn’t a punishment for them. It’s a policy for you.

Boundaries get framed as something you do to another person, which makes them feel aggressive and hard to say out loud. They work more like a rule about your own behavior: what you will do, what you will not be around, when you go home. The other person stays free to do whatever they do, and your part is already decided.

Phrase one that way this week. Not you have to stop, but I am going to leave when that starts. Then follow through calmly the first time, because the first time is what makes it real.