What's destroying the MOSFET in my buck-boost converter?
The body diode of the p-channel mosfet is forward biased, so it will always conduct through L1 which makes it fry: swap the drain and source of the PMOS.
Figure 12 of https://www.allaboutcircuits.com/technical-articles/analysis-of-four-dc-dc-converters-in-equilibrium/ and some other pictures on the internet incorrect as well.
The mosfet driver is missing its input signal.  
Pin 8 and 5 are floating, but should both be connected.  


  The ground pins are the return path for the bias current and the high peak currents that discharge the load capacitor. The ground pins should be tied into a ground plane or have very short traces to the bias supply source return.  
  
  The VDD input should be bypassed to ground with a local ceramic capacitor. The value of the capacitor should be chosen based on the capacitive load that is being driven. A minimum value of 1.0 μF is suggested.