I TOTALLY understand what you are going through. Totally. If you are going to taper to avoid withdrawal you should probably go lower than 40mg.
I tapered off and am nearing the end of my detox. Tapering did help but I definitely still felt the bad stuff. Not as bad as when I did it cold turkey though.
taper lower and slowly. You sound like you would benifit from suboxone though because you said you have tried to quit so many times. Good luck