Are we talking about the movie or the novel? The movie is nothing compared to the novel. Read the novel and it's one of those novels that you'll never look at life or people the same again.
In the novel, Mike does want the family to slowly become legit, he just has to move through all the dark stuff before hand, but he can't see what he is becoming and that it just won't be possible. The self-deception is part of what makes his transformation so powerful.
Kay in the novel: INFJ. In the movie, she's a totally different character more like ENFP. The Mike and Kay in the novel would never reach the point where Mike slaps her. Kay sees what he is and accepts it in the end. She sees his self deception and through her, the reader does as well.