I had exactly your same overcarbonation problem with a pale ale earlier this month. Sugar for 5 gal, but only 4.2 gal bottled.
I experimented with opening room temp bottles and then recapping 2 bottles immediately, 2 bottles after 5 minutes, and 2 after 10 minutes. I then let all 6 bottles sit at room temp for 2 days and then chilled for 2 days. All six improved dramatically over the original overcarbed bottles. I did not notice a big enough difference between the 0 minute recapping and the 5 or 10 minute recapping to make waiting worth it.
For the rest of my bottles (~35), I did exactly what Coastarine suggested. I lined them up, sprayed the tops with sanitizer and then popped the cap on each of them. I then recapped them in the order that I opened them. A few of them foamed a little, but I lost almost no beer. It greatly improved my ale although it's still a little more carbonated than I would like. My pours went from 10% beer/90% head to 70% beer/30% head.
I hope that helps. Good luck.