At the moment, it's just after midnight and I've been reading your posts for about an hour, getting a feel for your situation and wondering whether to ask you about this.
I'm currently working a summer job and I met this amazing girl, (name omitted for safety reasons), who happens to have multiple personalities. It's been around a month and even though I suspected it, and then she told me about it, yesterday night I met her other personality for the first time and it was probably the most bizarre moment of my life... both personalities know the other exists, both have issues with each other (the "original" has no issues while the "intruder" is aggressive and nymphomaniac). Having had conversations with both and seeing how they act I saw that multiple times today she has gone from one personality to the other.
What I wanted to say is, ordinarily I don't know what I'd do about this, but your post has given me the courage to try my best with her...
Thanks for posting all that you did... I appreciate it and it has helped me understand my situation and what I might be facing later...