Keep old disappointments out of a conversation about one new mistake.

One error can act as a doorway to every previous one. A conversation starts with tonight and within minutes is covering three years, and the other person, faced with a list, loses the ability to address any single item on it. Nothing gets repaired, because a person can apologize for an event and cannot apologize for a history in one sitting.

Deal with the thing that happened, and only that thing. If the older material still weighs on you, give it a conversation of its own on a calmer day, when it is the subject rather than the ammunition.