Dmax is a hell of a puller, aka, I smoked my trailer brakes

Your trailer brakes were energized with full battery voltage.
They engaged but didn't lock up otherwise the wheels would not have been spinning.

Worst case......new drums, new brake assemblies and new bearings

You will need to inspect each wheel (brake/bearing assemblies).
Brake shoes worn out
Drums scored
Brake magnets damaged from full voltage
Bearings/races scored from high temp
Bearing grease burnt up
Spindles scored

Tires flat spotted