So, it appears the damages are more severe than I thought. What appeared to be a bent crankset is slowly turning out to be a bent rear triangle: The entire chain- and seat-stays are now at an angle to the front triangle. Luckily the bottom bracket shell is still pointing the right way - the warps are at the seatstay-seattube connection and at the chainstays, rather than the entire seat-tube and bottom bracket being bent.

What essentially appears to have happened is that the sudden halt of the cranks transmitted such a strong force through the chain, that the wheel's inertia warped the frame.

Ugh, I lost my commuter for a few days.