Is what the questioner feels—a constant fear of death, palpitations, shortness of breath, loneliness, and an unwillingness to do anything—a delusion or a reality?

Calamity afflicts the prophets, then the righteous. You should consult a doctor regarding your condition. If it is not an organic illness, then you must perform ruqyah as prescribed by Shariah. To learn what to say when startled from sleep and the adhkar (remembrances) of sleep, the treatment for jathoom (nightmare), the treatment for delayed marriage due to magic, envy, or other causes, and how to get rid of obsessive thoughts, please refer to the fatwas related to each of these topics.