Oh by the way, can I ask how you were able to stop it?
just kept moving forward, going to class, going to work. When I felt incredibly distressed, Valium was somewhat calming, but didn't really change the nature of the DP/DR in any meaningful way.
Truth be told, I don't really know if it "went away", so much as I more or less integrated all my sensory experiences again and stopped feeling like anything "abnormal" was going on. I still get that glass-wall feeling from time to time, but never very severely or for very long, so it doesn't really faze me.
Stuff like meditation was absolutely impossible, and perhaps even counterproductive, during that period... but I will say, people with meditative experience in general, usually seem to have a better grasp on how malleable the mind is, and how much our thinking can change our experience. When I was deeply in the DP/DR hole, I remember my mother telling me that obsessing about my state of mind seemed to be hurting. Specifically she said something like "if I myself started asking 'What is real? Am I real? What is I?' over and over again, I would very quickly become very distressed, or at least alter my consciousness significantly".
That advice didn't seem especially useful to me at the time, but with ten years of perspective, I don't think she was wrong. Which is not to suggest that "incorrect thinking" creates DP/DR -- only that consciousness is a cascading set of feedback loops, and so distressed states of mind generally have cyclical self-reinforcing machinery as part of their basic nature.
My best advice is, do whatever you reasonably can to stay calm and comfortable, go about your day to day routine as if nothing were wrong even if you feel like you're alone on an alien planet that doesn't make any sense anymore, and try to have some faith in the ability of your mind to accept and integrate your sensory experience. Avoid all drugs and alcohol if at all possible.