@Suruti, strangely Devi Puran doesn't even mention this neither Devi Bhagvat.
According to Devi Puran When Sati at the yagya gets angry at her Daksh, thinks I can finish every one here including the Devas in a second. But killing Daksh will be apitru hatya. She creats a Chaya-Sati fromher, tells her to destroy the yagya & she goes back to her Loka. Shivji carried this Chaya-Sati's body & roams in the world. When Vishnuji cuts her body with his discus. Shivjitells him at least I had Chaya-Sati with me, you couln't see even that, you too will be seperated froyour Chaya-patni. It is said that it was Sita's chaya which stayed with Ram. this clearly shows Sati had eneded much before Ram's birth. That's why they are showing it occuring mentally not in reality & have effects of a future events in present.I know past events affects our present & future but seeing future & experiencing effects in present is absolutely new to me😆