Law is a way to regulate relationships in a sick society where hand-written rules how to exist become the last resort. Law must be in people's mind but not on the paper.
Honour. This is what mattered for him more than anything else. He would never exchange his dignity for the sake of woman. For the sake of Family? Maybe, but these concepts are almost the same for him. He hit his wife when he got to know that she made an abortion. He has never excused anyone. Even Fredo, even Kay with whom he has lived almost all his life. He valued honour most of all and couldn't accept any form of betray.