“I failed the test” is an event. “I’m a failure” is a story you built out of one event.

Watch what happens in the gap between a result and a verdict. A bad morning gets promoted into a description of a person, and the promotion happens without any new information arriving. One version is checkable: you can look at the paper and see which questions went wrong. The other cannot be checked at all, which is how it survives.

Stay with the checkable version. Get the paper back out and mark which topics actually cost you the marks, then pick the one that cost most and spend forty minutes on it. A specific problem can be worked on; a verdict about your whole self cannot.