When you replay the argument in your head, play the other person’s lines fairly this time.

Replays are rigged. In your version their points get flattened into something easy to beat, and you win every time, which is why the replay never actually settles anything. A rehearsal where you always come out on top is entertainment, not thinking. It also makes the next real conversation harder, because you have been practicing against a weaker opponent.

Run it once with their best case instead of their worst. Give them the most reasonable version of what they meant, and see whether your answer still holds. If it does, go back with confidence, and if it does not, you just saved yourself a second argument.