Much as I hate to say it, you should seriously consider putting her down. I had a dog in that situation; constantly pacing the room whining, jumping and frantically looking for hiding places at the slightest disturbance. You could see in her eyes she was miserable, no amount of comforting helped. We didn't dare leave her alone in the house. I waited too long; she eventually seriously injured herself frantically clawing her way under a power recliner, and afterward was in such pain we finally had no choice. Your cat is clearly similarly miserable; don't wait too long to give her peace.