I look at this incident from a "what's best for society" point of view. I think the Mother should be in prison for conspiring to incite violence causing death because she disobeyed a custody agreement set forth by a judge in the best interests of the children and society. Men's relationships with children is as important as women's.
Her desire to whore around with a married man shows you that she is the lowest form of trash. The cheating POS hot head wanted to push the ex-wife's game to show how tuff he was. They were NOT recognizing the interests of the child or the Father.

I think the killing was within the criminal act of incitement, and thus no "self defense" consideration should be offered.