When you are angry, don’t assume that you have all the information, or that you know what the person meant by what they said. Far better, to ask for clarification. You might say, “I may be missing something, but it seems to me that you didn’t keep your promise.” Now they have an opportunity to explain, or to apologize.
Getting additional information is always a sign of wisdom. Don’t jump to conclusions or believe the worst. It only takes a few minutes to get the facts. So, ask questions before jumping to judgments. “I need your help in understanding this,” is always a good way to begin.