Scared- need help from scientists?

I think you're missing the point. As you yourself said, you have an anxiety disorder. That requires medical treatment and possibly also psychotherapy. When you get over your fear of asteroids, another fear will arise to take its place because of your underlying condition. So instead of worrying about asteroids, you need to find help. Modern medications, mostly some selective serotonin reuptake inhibitors, are usually quite effective in relieving anxiety.