I get an overwhelming feeling that i'm going to die. i feel totally disconnected from the world, spaced out and dreadful. anxiety or something more?

Need to examine: It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated.