That was messed up what he did in the end.
I know you don't like your sister-in-law. But why would you give her a box that has demons in it? I'm guessing he thought she knew what was in the box.
shareI think he blamed her for all that happened. I think this was a combination of (a) needing someone to blame besides himself or his wife, and (b) he and the sister clearly didn’t get along.
Sure she’s the one who got them the box, but I don’t think it was her fault. She actually had good intentions when she got it for them, since she in her voodoo ways thought it would help the pregnancy. So yeah I thought that was kind of a crummy thing for him to do.