Let's see if we can dispassionately and analytically explore this. I'm as serious as a stroke, because the subject matter is. I see articles like THIS far too often, and according to the links in the article, "family annihilations" are happening more and more frequently. I don't remember these happening in the 60's, 70's, 80's or 90's. Maybe I wasn't paying attention, maybe the reporting was lousy, or maybe they just weren't happening.
There's a reason I'm asking--I can understand incandescent rage at betrayal. I can understand bloodlust and wanting to kill everything because of anger. What I can't understand is a irrational rage so intense that you'd kill your own kids. I simply can't conceive of being so angry with your partner that you'd dismiss the value of your own children's lives in order to inflict pain/vengeance on your spouse.
If this chart is correct (Wikipedia) then the rate of killing spouses is falling but the rate of killing children is increasing in the last 40 years--it's getting close to doubling. Wikipedia claims about 900 "familicides" in the hundred years from 1900 to 2000 and the article linked above claims 227 in the last three years.
So, with all the solemnity and respect this subject deserves, what's your theory on the cause? Loss of "community"/diminishment of fatherhood? We're lab rats under too much pressure? Decline of psychological/emotional institutions bonding society together? "Moral decay" of a specific type?