The symptoms are all common to having a body react to over production of adrenaline.
"Claire Weekes "Hope and Help For Your Nerves"
Second this, if your dad can possibly get exe rise, if possible long walks, this help mucho, any activity will help. Dealt with Depression, mostly brought on by anxiety for many years. Sitting in a dark room, staring at a wall is adding to the spiral, get him into sun light. Long term care facilities, at least in NYC are warehouses. He needs some activity no matter how "depressed", tired, scared etc he feels. Some of the benzo drug, short term can cut down on anxiety/fears, very fast acting, ask about Ativan.
"While the psychiatrist did try him on several meds she only kept him on them for about 3 weeks"
What, are they short on pills? most anti Depressives take 3 weeks to kick in.
"All he can say is that he's so scared and he doesn't want to live like this. It isn't him and he's ashamed."
If your Pop, had a leg wound, would he deny it part of him, no, he would have it treated. Just as he would likely help someone if they had a temporary illness. He feels week and vulnerable now, but this episode is but a small part of his life; he is totally correct this is not him, it is fear which he is reacting to. No one wants to die, but we can go to extremes when we are in pain, drinking anti freeze is not an answer.
Get him the Claire Weeks audio.