but this is one of the times I kick myself for having bought a Mac
To be perfectly honest, once something is corrupt, its corrupt. I doubt very much it would have made an iota of difference if you were running Windows rather than OS X on your computer.
I bought a couple of pen drives SPECIFICALLY to be able to make backup copies of what was on my SD cards in case I lost them
For your future reference, pen drives are
NOT an acceptable backup mechanism under any circumstances. I wouldn't trust them any more than a CF/SD/XQD card ... they are intended for
very short term temporary storage.
I selected all 852 pics and vids and hit copy and then tried to paste them into the pen drive;
Next time, don't put all your eggs in one basket. Smaller cards and frequent rotation is the secret, the minor inconvenience is very much worth it for the very reasons you have discovered.