Set a boundary in anger and you’ll probably need to set it again when you’re calm.

Anger is good at getting a line drawn and bad at getting it kept. What people remember from a heated version is the heat, so the next day the conversation is about how you said it rather than what you said. The limit itself never really got heard, which puts you back at the start with extra repair work added.

If you already said it hot, say it once more cool. Same words, flat voice, no apology for the content. And when you feel the heat arriving, you are allowed to hold the conversation until tomorrow. The limit will still be true in the morning, and it will travel better.