You have mine.
I'm someone who has been there. I lost part of my foot in a lawnmower accident many moons ago. As a result I have made friendships with other people who are amputee's for one reason or another.
He will likely go through the same stages he would if someone close died. After all he has had those fingers for a long time. But my point is expect his moods to change over time. Anger, grief, and depression are some of the stages he will probably have. Maybe some more, and the duration of will vary. Expect this and patiently help him through it. Again its very similar to the loss of someone close to you.
When he begins to rehabilitate he will probably go through some more ego driven feelings. Shame, embarrassment ect. Unlike my foot, its hard to hide your hand. In the distant future I would guess he will be more excepting and use it as a ice breaker or instructional aid. People will stare and expecially little kids. Get used to it. Its going to happen.
Doctors can do some amazing things now. So you may also be surprised what his options are.
One thing that turned me around was being in a big hospital. That's a place where you really appreciate how good you got it and how bad it can get.
Its tough. You, your father and family are in our prayers