All righty then.
Bougainvillea CPR did not seem to help much. After much deliberation, a pre dusk decision was made to attempt life saving measures in the form of radical surgery.
After trimming off all the branches showing no signs of life, this is what my plant looks like now. Some hardy leaves survived the deep freeze, but as you can see, not many.
I did find some new growth hidden in the briar patch that this bush had become. I hope the growth will be enough to stage a revival of this plant to its former glory.
I am off to the fish store.