Tang Feng didn't know at the time that the Tang Family was facing the crisis of annihilation, but Murong Qinglan did. Tang Jianjun had called her and asked her to inform Tang Feng about the trouble he had caused.
Murong Qinglan initially didn't want to bother with her brother-in-law, but his words were so severe that she couldn't help finding it strange. Logically speaking, since Tang Feng had already left the Tang Family, even if there were enemies, they wouldn't strike at the Tang Family because it would be pointless. According to his temperament, it didn't matter to him whether the Tang Family existed or not.
However, this was something she had to tell Tang Feng. No matter what, he had to decide for himself, so she whispered a few words in his ear.