I knew it. I already said this in the early chapters but for me sheriel that we know is the real sheriel but either her life or her son's life ended in a tragic way so she made a bet with the witch and that's why she regressed but with incomplete memories. Plus i remember in the first chapter we see à lady with red hair saying to her ''are you ready to start again and let's make a bet '' or something like that so i'm sure now that's more or less what happened and that lady was the witch.
