Zhen Xiu knew there and then that Lu Qiqi was hiding a baby in the orphanage which was related to her by blood so it can only be her kid.
After trying to pry the kid she felt the repulsive action of his spiritual power protecting him and was hurt because of it. Now there was only a little amount of spiritual power left in our body that she can only utilize by completely destroying her space.
It was not a big deal to her as in this world everyone is normal except for a few cases which are too easy for her to feel worried.
Zhen Xiu was worried that Lu Jian might hate her after knowing her plan and how she treated him; it was difficult for her to confess her truth as she didn't want to repeat the same mistake that he did at one point in his life.