There is a very good chance I overpitched my yeast by… a lot. I’m seriously too embarassed to even post the figures. Anything I can do to salvage the beer from under-attenuating?

it isn’t a complete given that it will underattenuate. the two times I overpitched, I had no problems with attentiation but i had problems with the yeast cleaning up the byproducts at the end - namely acetylaldehyde. I would let it ferment cool for the first few days and then let it warm up to the low 70s at the end and leave it sit for at least 2 weeks post fermentation.

Come on, how much? It takes a LOT to over pitch. Are you sure you really did?