She knew how painful it was to contract this disease; she didn't want others to suffer like she did.
Ye Xingbei and Situ Jinse had done her no wrong; she didn't want to harm them.
So, what she said was true.
She had replaced the blade with a clean one, and she hadn't smeared her blood on the wounds of Situ Jinse and Ye Xingbei.
Situ Lanyu, that scum, judged her with his filthy and vile thoughts.
Situ Lanyu assumed that because she had contracted this disease, she must be bitter and unwilling to accept it, eager to harm others to drag them down with her, to make others suffer the way she did—thus, he didn't guard against her.
She replaced the blade with a clean one.
She successfully deceived Situ Lanyu.
She truly did not harm Situ Jinse and Ye Xingbei.
Every single word she said to those people just now was true.
Now, she was terrified.