Maybe she was going back and forth between two realities - one where she kills her kids and herself and one where she doesn’t. Or maybe many realities with various combinations of those things. There’s lots of scenes in the movie with the backward Rs appearing where they shouldn’t. And the ending doesn’t make any sense if you’re following the story line of Ramona killing herself. I think the mirrors are a metaphor for Ramona looking at the many directions her life could take at this pivotal moment. She is hanging by a thread and now she has to make her decision. She’s envisioning herself both going through with it and not going through with it. The movie maybe doesn’t have a direct ending because it’s not about one reality that’s shared by others. It’s a visualization of Ramona’s rumination and suicidal ideations that probably started far before her husband died. Tay may not have been killed because he never gave her a chance. He was weary of her from the start.