Hello notthatkidw0wzer: I noticed this is your first post here on PC. So... welcome to PsychCentral!

I hope you find PC to be of benefit.
I'm sorry you are having such a difficult time.

You wrote you don't want to self-diagnose. Likewise we here on PC cannot diagnose you either. Mental health diagnosis is a job for a mental health professional. You mentioned you saw a mental health therapist. But the therapist told you the other world you see isn't real, so you got mad & walked out.
You also wrote you know the other world you see is real. I won't tell you the other world you see is fake. That's not for me to say one way or the other. The important point here, it seems to me, is that for you it's real. Perhaps the more important consideration is the distress what you are experiencing is causing you. You mentioned everyone thinks you're crazy, whenever you open up to them they get scared & go away, & that you're desperate & confused. That would all certainly be a frightening way to live.
Unfortunately I don't know as I have any particularly creative suggestions for you as to how to deal with this. The obvious thing is, I suppose, stop talking about this with people who will judge & abandon you for it. I'm an old man now. And I don't know a lot about either psychology or relationships. But one thing I feel I can say with confidence is there are simply things you can't talk about with people in general. They won't understand & they won't stick with you for very long if you continue to talk about it. That's just the way it is, in my opinion.

(If you're into such things as art or creative writing or music, these may be alternative more socially acceptable ways of expressing what you experience.)
And that is, to some extent, where therapy comes in. A skilled therapist is going to be willing & able to work with you to help you figure out how to live your life day-to-day in this world even if you do feel you are also experiencing another world other people don't see. I don't know if telling you your other world is fake, as that therapist you saw did, was appropriate or not. I'm not a mental health therapist.

My own personal non-professional opinion is that it was probably not. But then not every therapist works well with every client. Sometimes it can take a few tries to find the right therapist for you.
So, as a result, my thinking on this would be that perhaps was is needed here is for you to try and find another therapist who is more compassionate & more willing to work with you rather than to challenge you right off the bat, so to speak. Maybe that kind of tactic works with some people. But it obviously didn't work with you since it just made you mad & caused you to walk out. At least these are my thoughts with regard to your post. I wish you well...