I forgot the title for this manhwa. It's about a female lead who gives up her magic so she can have a child. She is married to the emperor, but he only married her because she was powerful. After she lost all magic, the emperor ignored her, so she did the same with her child.
When her child grew up I think he killed her. She was very sad, so she traveled back in time so she could make her child happy, then she became a spiritualist.