Wearing My Sister's Wedding Dress and Walking into a Man-Eating House

I am married to my sister's husband. On the wedding night when the candles were burning, he gently wiped away my tears: "Don't be afraid, I will treat you well." But I know that three years ago, my sister heard the same words, and then died in this bed inexplicably. The sawdust between the fingernails, the medical expenses that stopped abruptly in the account book, the bloody writing at the bottom of the well... This house can eat people, but it can't spit out bones. And the biggest mystery is: my husband is the one who helped me dig my grave—— Or the one who dug my grave with his own hands?