I think what we are seeing is a woman whose drinking is quickly spiraling down into full blown alcoholism. A lot of the emotions, reactions and personality traits we are seeing -- narcissism, defensiveness, denial, lying, blaming others, etc. -- are very typical among alcoholics. Especially those who have not yet admitted to themselves that they are, in fact, alcoholics.
I think the big thing she has been trying to hide all along is her drinking. People are reading those actions as a sign of guilt in the disappearance of her daughter. Her guilt is about her drinking.
As for JI, he is the co-dependent in this family afflicted with addiction.