Kate,
Your dad is in for the fight of his life, but there are many people on these boards who have made it through and he will too. I got a lot of comfort from the cards and letters I got in the mail every day. So if you feel you can't visit him in person, write him a note, have the kids draw, send a card. Getting the mail was the highlight of my day for several weeks during my recovery.
Good luck,
Barb