Black Swan and psychosis

I watched Black Swan last night and it made me incredibly anxious. Psychological thrillers or anything to do with severe mental health, especially psychosis or hallucinations, have always terrified me more than gun shooting, physical violence and car chases, though I don't like them either. I remember studying psychopathologies at university and each lecture would bring me more anxiety as I pored over the symptoms to see how many of those on list I could relate to. I know lots of people who did this with the medical dictionary in our sixth form library, but for me, it's the so-called mental illnesses that frighten me more than the physical ones.

I have a feeling that I have more direct knowledge of them, as well as theoretical knowledge, than many people, so I wonder if this means I am less scared than most because I understand more, or more scared than most because I can't ignore these issues and have more contact with them (or perhaps, obsess over them!). Certainly reading about treatment and management helps significantly, but it's the many thousands of despairing untreated people that my heart breaks for. And, what if, one day, I become one of them? One of the untreated: slowly, invisibly and inexorably fading away in a darkened room, or drinking themselves to death. I would hope that those who love me would be there to look out for me, perhaps more successfully and confidently than they have in the past with (slightly) more minor crises, but you never know because everyone has their own life and their own issues to focus on. If you're looking the other way, for whatever reason, you may not see.

What is it, I wonder, that makes mental illness so much more frightening than physical illnesses? What is it about going mad that instills such fear? Is it the idea of losing your 'self', perhaps? I know that the idea of taking most of the drugs around always made me anxious when I was younger, for that very reason - what if I lost my 'self' somewhere along the way and never found it again, or never found a new one?

I feel compelled to read, watch and write about the very things that terrify me the most and I rather suspect that this is so I can explore them, to understand, to know. Knowledge and understanding, to me, are security.

Then there's the whole debate about madness and spirituality. For the scientific, anything that is not science is hallucination, whether this is just a random experience or part of an illness. For the spiritual, it often feels very hard to know where to draw the line between spiritual experience and psychosis, certainly when non-believers become aware of these experiences. I certainly don't know where this line lies. Any thoughts concerning this particular issue would be welcome. I'm deeply curious about this.