Final answer:
Dulcie tells her sister Josephine and Richard about Teresa's accidental death. Meanwhile, Mildred, in a different context, tells Harold that she had to reveal what she knew related to a significant situation.
Step-by-step explanation:
After talking to a lawyer, Dulcie decides to tell about Teresa's accidental death to her sister Josephine, whose broken sentences and veiled hints reveal the incident, and Richard, who was present in the newspaper office when the news of the accident was received.
In the context of the provided text, it is Mildred who encounters a situation where she says, "I had to tell all I knew." This indicates that she chooses to reveal something significant, perhaps related to a case or circumstance, to Harold after a period of contemplation and a change in her behavior following the incident.