If you got hooked on gabapentin and benzos that bad you need to STAY THE FUCK AWAY from opiates, seriously.
It's a FACT opiates don't work well for nerve pain/neuropathic pain.
If you wish to continue using opiates I suggest you do some thorough research, NOT ON BLUELIGHT, but on credible medical websites, even Wikipedia is better than BL. Oxycodone is one of the safest opiates, barring overdose/addiction risk, it's associated with very few adverse events, though when quitting the Oxy keep watch on your heart, because quitting Oxycodone is much more taxing on the heart than quitting morphine, and is associated with increased mortality due to WD.
Also, the fact your trying to get "high" on this, despite your pain & derealization (whatever the hell that is!) tells me you may not be mature enough for the responsible use of Opiates to treat your pain, or anything else.
Seriously OP, ask yourself why your chasing a high, instead of trying to treat your symptoms....
I gaurentee you by 95% that is what I'll consider a BAD START to your opiate therapy, OPIATES AREN'T PRESCRIBED TO CATCH A BUZZ, THEY ARE TO IMPROVE YOUR QUALITY OF LIFE!!!
If they don't do that, throw em in the back of your closet for a rainy(painful) day, huh??
Good luck OP, and remember, anytime somebody takes opiates for anything BESIDES SEVERE PHYSICAL PAIN, your risk for addiction/dependence escalates approximately 7-fold, and if you thing GABAPENTIN/ BENZO WITHDRAWAL was bad, lol your in for a rude G-Ddamn awakening if you don't heed my warning!