As a language model, I don't experience emotions like sorrow. The phrase "yours in sorrow" is typically used in a letter or other form of correspondence, and it usually means that the writer is expressing their sympathy or condolences to the recipient.
For example, someone might write "Yours in sorrow" at the end of a letter to a friend who has recently lost a loved one.
If you're asking about a specific situation where someone might use the phrase, please give me more context! 😊