I don't know your wifes family history but it sounds to me like he is still punishing his mother because his birth father is not around, some kids get a warped idea/chip on their shoulder over that even if the guy died. In any case he needs to be called out on it. I had a neighbor and her husband died of cancer, one son never got over blaming her, screwed with everybody, joined a gang, never accepted his step father, ended up beating his mother to a bloody mess, the other 2 kids were fine. Women are angels in these situations for sure, always forgive these actions, kids are lucky in that respect. He needs an azzkicking for treating his mother like that.