You could talk about him as someone who does bad things, as opposed to a bad person... this is a fine distinction, but I think an important one. Someone who does bad things does them for reasons that aren't always understood (they were hurt in the past and developed bad ways of coping, etc). They are not bad people. That way she can know the truth - i.e. that he acts in violent ways, and does things that are hurtful, like ignore her. But she can also learn to look at him with some empathy that will let her possibly forgive him when she's older.