Kinda funny how comments for this film went consistently downhill, now add mine. I think the script could have been saved by better acting, and the acting by a better script. Together, it was difficult to watch, and I don't flinch from such subject matter.
Sigourney was the best part (I thought the relationship between her and her surviving son was pretty much the only new thing this film offered to its genre) but even she lagged. Can't blame her, who knows what takes were left on the cutting room floor by the director and/or editor. The whole movie had an "okay, that's good enough, let's move on" feel to it, when I KNOW there was more to be mined from the actors and the script, which did have some good lines and some interesting themes.
I don't think this counts as a spoiler, but a perfect example is the scene where Sigourney marches up to her son's supposed tormentor's house and has this look on her face and I thought "that's the face of someone who is overacting what it's like to see someone living in a mobile home" and sure enough, next shot, meant to shock us I'm sure, bully lives in a trailer as opposed to a nice house, like hers.
As many other posters have pointed out, there are SO MANY better movies with similarly airy scripts about similarly messed up families that hit the notes better -- "Celebration" probably being the ultimate example that I've seen.