Qing You was a high-ranking member of Gu Sha Mercenaries. To be honest, her identity called for absolute secrecy.
Gu Sha was an international mercenary organization and Qing You, as one of its executive members, needed to keep her identity confidential.
Of course, Qing You wanted to tell Liu Tie and Liu Ziyun the truth purely because they were her family and the closest people she had. She wanted to be honest to dispel the misunderstanding.
Being honest could come on multiple levels. One was coming clean completely and another was for Qing You to only disclose that she used to be an assassin. Both meant more or less the same thing but it was obviously not the right move to spill everything about Qing You's identity.
She was, after all, Gu Sha Mercenaries' high-ranking member, and the organization had its rules. Yun Jian had been the one to set them and even she could not break them easily—what was more, this was Qing You.
