Whenever my wife and I have a serious disagreement, she thinks I disappear for a walk to calm down. I do calm down, but I also rehearse my apology out loud.
I literally walk around quietly saying things like, "No, that sounds defensive," and trying again. I'm terrible at expressing myself in the moment and terrified of making things worse. She sometimes compliments me for knowing exactly what to say after conflict. If she knew how many practice versions exist, the mystery would disappear.