How do I figure out what is real danger and what is something I'm imagining?

Well honestly to the body there is very little difference. and the general thing with anxiety and panic disorder is perceived danger and not actual danger. I don't know your context, but take a picture or movie of it, or have a friend to look at it with you. I can't really answer more with out more details.

Ask people around you, look for evidence or clues, next time when you think you are imaginning pinch yourself and see if its real

Real danger will hurt you and if people are around, other people will react and the danger will stay. Imagination won't hurt you, other people won't react and imagination will go away.

Everyone is different. There is no one answer fits all. Perhaps you can seek help through a therapist or counselor.

It's really hard to tell! But if you can tell the difference, it's almost like when I'm imagining the danger, I'm not really in my own body. Rather hovering nearby, kind of watching this scene happen. Real life always has this way of just coming back & hitting you...

Maybe give me a little more, an example of a situation you are referring to. You might want to talk with a qualified counsellor who would know how to help you sort this out; I can help you with a referral.