Broke new piston ring...help.

I've been with my parts guy over 40 yrs, and I'd tell him exactly the truth, ask him if you can order a whole new set of rings to replace the one you broke, order a single piston ring set, and return the complete second set when the single ring set arrives.
You'll pay restocking charge.
If not, sell the second set here.
I have done similar, but I have spent a lotta $$$ there.
Good luck .