Why am I destroying my MOSFETs?

polymorph:
A diode across the inside of the MOSFET (the intrinsic body diode) is NOT the same nor will it work the same as a diode across an inductive load.

True. It will only absorb the energy that might damage the MOSFET [i.e. it only protects the MOSFET]. It won't absorb the rest of the energy that could damage other devices in the system.