That is the biggest pile of shite I've heard in a long while. Your psychologist needs shooting. In my experience, the prognosis for drug-induced DP'ers is better than those with chronic, long term DP. (Diclaimer - that is not to say that non-drug induced DP'ers cannot recover..)
If you are not 'prone' to DR/DP, that is without any serious underlying neurotic problem, I truely believe that once your brain chemistry has returned to somewhere near normal after taking drugs, you have an excellent chance of recovery.