It is as if the world narrows down to the grip he has on Shuoyue, white-knuckled in such a primal reaction of revulsion that he tenses up, standing straighter as he hears the news Jin Guangyao was here and it obliterates the importance of anything else. It hurts, somewhere laced in wire around his ribs, to think of a-Yao walking and talking and being again, he cannot stand the notion of it; it makes him nauseated in a way that feels too much like cowardice and cannot be shown to others. Even the memory of him drove Xichen into seclusion. Despite being told about Lady Wen being alive, it never occurred to him that these same streets could have been walked by the one person who shredded his self-regard to tatters. He does not even want to be on the same physical plane where that ghost walked first, even if it is gone.

Wei Wuxian is saying something about Xichen sticking close to Wangji and, yes, he will, but also,

"What did he do while he was here?"

A-Yao. What kind of rage would you bring back to the waking world with you, a-Yao?

Xichen does not admit that Jin Guangyao already stalks his nightmares, let alone his entire life.