Good movie until the last 10 minutes

I think Hathaway just lost her mind when she lost her son. It still happens to some people who lose a child, especially if they can't have another one like Hathaway couldn't. They just can't cope. In addition Hathaway felt extreme guilt over the fact she didn't even know her child was on the terrace while she cleaned the house and felt it was her fault, which it really was.
Obviously Hathaway's response was extreme, she wanted Theo at all costs. Once her husband told her to stay away from Theo and his parents, she turned on him. And then, of course, did what she had to do to make Theo hers at the end.

I didn't care for the ending because it rewarded murder and insanity. I just didn't like such a bad ending after seeing what I thought was such a good movie. The acting, atmosphere, and storyline were excellent, and then that ending! Very disappointing!

I saw it today and it was so overheated campy. Hathaway and Chastain chewed the scenery, while the actors who played their husbands portrayed their roles with realism and restraint. Quite a contrast.