That thing that Sima You Yue did before she left, it was as if she gave them a head-on blow, knocking their heads ruthlessly. A moment of recklessness blew them up.
She could kill her attackers easily without wasting her own spiritual energy, by opposing her, wouldn't that be seeking their own death?
Furthermore, she had the whole bird clan as her back up.
Those people who were sent to kill Sima You Yue were summoned back by their forces, those masterminds who sent the people to kill Sima You Yue rejoiced, it was a good idea to get them to be dressed incospicuously so she wouldn't know.
Next time if they want to seek revenge, they could only do it shadily, they can't do it in publicity.
After Sima You Yue left Heavenly city, she didn't head straight to Divine Devil Valley, instead, she went to Heartbreak Valley and brought those people who were willing to join the clan after taking antidote, out from Little Realm.