Lydia, I think the answer is the ghost protecting Thup. I think, she is the wife now that we now that the nurse ghost is the affair. So Thup is... well but not the sick son. And if the nurse ghost is attacking everyone, it's because she wants to protect her lover and her son, like Thup said she doesn't want people finding the truth. And the ex cop doing this can control her, I think. I have an idea who might be the ex cop, but no idea who is the sick son, I thought first it was thup but no. That's what I am thinking up until now.