I really don't understand this long running idea that Chris will somehow "snap" and murder Barb or go on a killing rampage at the Game Place or some such thing. Chris has never displayed anything but utter cowardice in the face of confrontation. The only people in danger of harm from Chris are the ones who stand in front of his car while he's trying to flee the scene.
As for Chris murdering his mother, I find that about as likely as Chris becoming fluent in Urdu. He may eventually work up the nerve to disobey mommy, but even that is unlikely. If he's pushed hard enough, I suppose Chris might retreat into his safe place for a long period of time in a sort of traumatic fugue state. I guess that would be a plausible example of Chris "snapping."