The Ending Of Missing Explained

Grace's actions seem rash until the entire story is revealed. While the internet believes Grace changed her name due to something sinister, it's actually a sad story. She used the drugs to put her husband in jail because it was the only way she could get away from his abuse. 

The rest of the video clip, which is cut off at the start of the film, shows that James is an abusive person. In digital communications between them, he uses common manipulation tactics in abusive relationships, such as saying that won't be able to provide for herself and that he will always find her. Search histories re also glimpsed, where she has looked up how to cover a bruise and how to report domestic violence. 

Sending him to prison for possession ensured he had a longer sentence and gave her the opportunity to escape. Before taking on a new identity, her name was Sarah. She created a new life to protect herself and June, deleting her previous accounts. She left her family behind and moved to a new city, ready for a fresh start.

It's a vivid depiction of what victims of domestic abuse sometimes have to endure. They find it difficult to report their spouses, knowing the law isn't always on their side. She found the courage to report him for a different illegal action and forget everything and everyone she knew. It's a difficult decision to make, but one that ensured her survival.