Thorns + Pyromantic Pact + Crown of the Pale King

Pyromantic Pact counts as a "hit" for the purposes of Crown of the Pale King's thorns modifier, which triggers thorns onto the source of said damage: you.

This interaction instantly kills my character which has 75% Fire Resistance and is wearing Cloak of Flames for 40% Phys damage converted to Fire. Without Crown of the Pale King on, I survive the hit with the assumed 75% ehp remaining.

I currently have 1036 health and 117 energy shield. I also have 709 armour at 40% estimated phys reduction and a 40% chance to block (if thorns is even blockable, which I doubt).

My thorns damage at the point which Infernal Flames damages me:
Physical Thorns (48 - 68)
Fire Thorns (51 - 71)
Total Thorns (99 - 139)
Thorns Crit Chance (22.5%)
Thorns Crit Damage Bonus (150%)

Even if this interaction is intentional the phys thorns should be 40% converted to fire, along with the fire thorns of course being resisted at 75%. Thorns seems to bypass any damage conversion or resistances at a minimum, yet also seems amplified in this situation. Perhaps multiple instances of thorns are procing here? Not sure.

Does it happen with any amount of thorns?
I wonder if perhaps it triggers from itself - as in:
Pyromaniac pact hits you thanks to the helmet, triggers thorns
thorns counts as a hit against yourself because of the helmet as well, triggers thorns again - rinse and repeat