That's very interesting information to have, especially concerning your great great aunt. As far as I know, no one in my family has ever been hospitalized for MI (though it's definitely present in milder forms). Apparently I have a "crazy" great great uncle who used to run around outside naked, but I don't know if he was ever hospitalized or even received any kind of treatment for whatever was causing his behavior.

Your mom probably is in denial, which is unfortunate for your sister. Is there anyway that you can get her to a psychiatrist yourself? It's a bit unexpected that an AD would relieve her psychosis; usually patients with psychotic depression need an AD and an antipsychotic. Which causes me to wonder if the hallucinations truly are gone, or if she just stopped talking about them when she went on the AD because she didn't want to worry your mom any further. I wish the best for her.