Yes I have this although that particular 'disorder' is not so much a disorder (just another way of labelling) as it is a common symptom of long-standing depression or anxiety. Some people disassociate from their problems by creating fantasy worlds in their heads.
I've done it since I was a kid and I still do it now (age 27). I have characters in my head I'm far more attached to than real people. The reason my therapist gives me, and that rings true for me personally, is that I disassociate from everything and tend me depersonalised/derealised. I inhibit my emotions so much I'm not even aware of them and can think of traumatic incidents in my life without so much as a hint of sadness. It's like watching actors on TV, it's not really happening. Fantasising is a successful coping mechanism for children (and adults) but can become maladaptive if you rely on it. As I do, and as a lot of inhibited/disassociated people do.
If I were you I wouldn't think of this as yet another disorder. Your real 'disorder' is that you are unable to face up to the real world for individual reasons of your own, probably linked to events and treatment in early life. I was too ill to function for large proportions of time between the ages of 13 and 25 but I'm so much better now my therapist thinks this is the end of it for me forever.
The more disorders you diagnose yourself with, the harder it seems to overcome. But actually, recovery is totally possible and this is just a symptom of one underlying problem. Speak to a therapist about it, definitely.