I'm so sorry about your Dad, our thoughts and prayers are with you and your family. It does, by the article, sound like a terrible accident. The lack of remorse thing.... I honestly can't know how the man feels. I have a guy at work who 5 years ago killed a woman on the 405 in Orange county. It happened at 4am on his way to work, the lady had dropped her cell phone and while reaching for it on the floor spun out and stalled the car. She then got out of the car and got hit by my friend, she was also legally drunk. My friend was not initially emotional about it, but more analytical. Months later he had to do quite a bit of psych therapy to deal with his feelings and it really ate at him.
The Point, and sorry to drag this on, is that people react differently to incidents of this magnitude. Like I said....I can't KNOW how this man feels, unless I were to have a heart to heart chat with him. Hang in there Brother....and know you have people who care to give you what you need