Spanish phrase
No debí hacerlo.
Meaning
I shouldn't have done that.
When to use it
It shows regret for a past action. It often appears when someone apologizes and admits that the action was wrong.
Example dialogue
Perdón por borrar tu dibujo. No debí hacerlo.
Sorry for erasing your drawing. I shouldn't have done that.
Estaba enfadado, pero ya está. Hagamos otro.
I was angry, but it's okay now. Let's make another one.