Philippa by Mary Louisa Molesworth — Read

But as for "never mentioning it again?"

Before Philippa fell asleep that night, her mother was in possession of every detail of all that had happened since they parted. More, far more of course than Evelyn knew, or ever would know. The younger sister was not one to do things by halves, and when she gave her confidence it was completely given. She had confided in her mother all her life, and the longing to do so now, even at the risk of causing Mrs Raynsworth increased pain and mortification, was irresistible.