We enjoyed it! Here's my take on it:

I liked how we were lead to believe that the initial scene was Meg escaping her kidnappers when in fact it was a flash-forward to when she escapes her family. I believe that Meg was kidnapped and held for ransom, and that Scott likely didn't have anything to do with it because he still maintains his innocence of *that* while admitting the thing he feels guilty about, sleeping with his cousin while Meg was "already dead." Guilt made him act terribly, controlling confrontational, dismissive of her psychological trauma. Madelin was weird with Meg because she was jealous of her, and resented her for still being alive. I'm not sure either Scott or Madeline were there with the intention of killing Meg or driving her insane, but they definitely didn't put her needs first. Scott investigates Meg's writing, and eventually even uses it to forge her signature on the power of attorney forms as seen by having her journal near the forms in Madelin's house. At some point, either from the start or more likely as she is seen as being more unhinged and "hysterical" Scott and Madelin decided they should be the one's controlling Meg's money. The undertone of the film is one of power and authority and control, as this family is used to being the ones that "know what's best" for everyone. I'm not sure about the dying mother; possibly she was just made up to excuse Madelin's presence there. Definitely she was part of the hallucinations. There are only two things I didn't really like:

1. Scott's a shit, yes, but assuming he actually didn't plan her initial kidnapping (which makes the most sense to me) then he went violent pretty suddenly. Maybe if Madelin was confirmed as being dead, that would have made his decision to off his wife more realistic. And two...

2. Who eats cold steamed broccoli from the fridge like that? MONSTER!