Why does he not realize the emotional and mental devastation he has caused? Can he change with therapy?
There are various ways of looking at this. I believe many batterers are in a dissociated state when abusing you. That means that he does not feel like he is the one hurting you, or he sees himself do it but its like a dream, or he sees that he does damage but he minimizes the depth and severity of the damage. It seems that there is also be a type of batterer who knows exactly what he is doing but I don't think that's the one you're describing in your question.
The kind of man you refer to is the more confusing type - he seems to be intelligent and grasp most of life but in this area he seems dumb, dense, or deliberately avoidant. He needs help to accept that he is capable of violence, and he may not either accept that help or be able to benefit from it. So far, results from therapy with batterers are not encouraging. Programs with the best results are comprehensive - including signing an unconditional "no-violence" contract, mandatory group attendance, individual mentoring and (later) couples work.
See list of FAQ.