Playing catch up...my thoughts on various discussions:
2) The theory that CW accidentally killed one of the girls --- I can't wrap my mind around that one. No sane person would do this. Accidents happen all the time. Parents have accidentally killed their children (i.e. backing out of the driveway and don't see the child behind the vehicle, or stepped away to answer the phone while kiddo is in the bath, etc). NO SANE PERSON would see the accident and then say, "well gee, oops. Guess I need to kill the other kids and then pretend they're missing." No. Sane people are horrified, screaming for help, calling 911, grief-stricken and pleading with God. JMO
3) I can accept that SW may have been overbearing, demanding, maybe even controlling and CW was more subdued. Maybe she didn't really respect him anymore so the snide remarks or disinterest came easily. That type of personality doth not a killer make. I just can't see her murdering her children, who appeared to be her world, to spite a husband she doesn't really like. If anything, that type of personality, upon finding out about CW infidelity, may be capable of taking HIS life because of the betrayal and humiliation. JMO