Depends on what her fate is, really. If she’s going to be killed by someone she can’t possibly defeat, then only YC’s strength, that can break common sense, really stands a chance. Or it could be something as simple as, “This is inevitable, I want him to be as strong and as indifferent as possible to spare him as much pain as possible.” It’s similar to when Huan Caiyi was pushing him away when she thought her death was inevitable. Could even be that her fate is tied to being his enemy and making him grow and she said what she said because she can’t force him to grow if he knows it’s a ploy so she could only reveal everything if the need for the ploy was gone, meaning he was already strong.
Was the “hidden danger” the main reason why HSDE left and prevented the Devils from entering? I felt like she left because she specifically wanted something like this to happen so he would grow in strength like crazy. Only when he stands at the very top could he possibly be completely safe and in turn leave her daughters in completely safe hands. She would need to leave for this to happen because no one is stupid enough to try anything while she’s around and her being around is causing too many problems with just her aura. He could never accomplish his strength gain with the Devils around either because he would get slaughtered before he had a chance and they would also cause too much trouble.
The reason he reacts weirdly to the skinny Yuanba dream is because Yuanba was only a skinny child until he wasn’t. He eventually blew up to a ridiculously burly size and, presumably, skinny Yuanba was during a time when Yuanba should have already been big and bulky. That, or it’s the fact that XQ was missing that threw him for a loop.
I’m of the opinion that XQ is being erased after the fact. The Mirror seems to operate on the highest level meaning it could theoretically create an entire person out of whole cloth, but with the way the story is going, it makes more narrative sense for her to be being erased. You also have to remember that only her actual existence seems to be gone, but her attributes seem to survive in some way. Skinny Yuanba apparently got her insane comprehension. Plus, we’ve only seen the Mirror affect other people in very specific circumstances. Yun Gu and Su Ling’er, who were both very close to Yun Che during the alternate timeline 2nd life that was created and then undone by the power of the Mirror. Yun Gu only had a sense of familiarity and was in possession of the other half of the Sky Poison Pearl, whereas Su Ling’er had a complete set of memories and was directly saved by Yun Che throwing the Sky Poison Sword. Both had extensive contact with the very Heavenly Profound Treasure that was brought over by the Mirror’s power to affect causality and Yun Che himself, the only known person for whom the Mirror has activated. This does not hold true for XQ. I’m thinking her fate will involve the Nothingness canyon/chasm/ravine that was in the God Realm of Absolute Beginning. Since Nothingness is above even time and space, it would erase her from ever having existed. Yun Che, being the only being to ever touch the Law of Nothingness, will be the only person who even remembers her and will eventually bring her back.
Not sure what sort of effect the 1st Heavenly Profound Treasure will have, but Ancestral God Arts are Law of Nothingness and are above Light(Life)/Darkness(Death) and even space/time so they theoretically should be able to reverse pretty much anything that happens.