Not enough Kevin

I just did not understand why he was so desperate to get away from his wife. They were supposedly happy and all he had to do was to tell the truth. He would have saved his own life as his family would not have even been in danger. If he had someone else then it should have been a part of the film even if it was small. I never believe these stories of the abusive spouse living a lie for so long at being a loving spouse. only to have had plans to at some point kill there mates. I know it does happen but in this movie it was not believable. And just what was he to do with his son, raise him by himself. Or kill him too. This movie had way to much of nothing turned into something. Just for the thrill factor.