It would first crush the jaw and push it until it pierces nasal cavity
Assuming she wouldnt suffocate or drown in blood by that point she would experience her spine breaking off from the base of the skull most likely

It would disable all organs including heart but she would probably be able to record increasingly darkening and flashy vision since her eyes would nearly come out from the orbitals, and the ringing sound in ears if any. Ears would be full of blood by that point and they would make the sound seem as if your ears were stuffed due to blood besides being already closed by pressure, so she would hear her heartbeat in artery and valves closing each beat, with blood making the sound comparable to a drinking straw full of liquid shortly before the spinal cord snaps

If the skull broke she would feel somewhat comparable to the void of the space sucking out everything and losing pressure in an instant, combined with extreme cold that new wounds feel and also a pain of such kind that dentists make drilling teeth with no painkillers. It would feel arctic cold and hurt so bad that your thought disables instantly from overstimulation by pain, all that assuming she can feel anything up until this moment

It most likely would be short with shreds of freshly broken skull sinking into the brain that would damage her beyond ability to crave for survival
Though the pain sensing neurons are in the bottom of the brain that would be relatively unaffected and the cortex that is doing fine

She would feel less pain after some 5 to 10 seconds due to lack of oxygen and sufficient blood, or heart does not work in which case she would enter this final stage earlier and be gone already, only subconscious would work and more primal elements like cortex and its cells trying to release the last bits of energy in their ATP to drive mad electric impulses to stimulate the rest of the brain back into life, the same method that people use electricity to revive heart, for the next few minutes until even they need to switch off once and for all not able to synthesise anymore

The rest of her organs would die within a day, all of them doing the same as cortex, sending impulses to the spinal cord which cannot forward them to brain anymore, and they too die.