Glad you got it out! I'm sorry about the plastic gear. I will just write a couple final notes for anyone doing it in the future.
You can't get the plastic gear out without removing the gear on the water pump shaft, so it is best to remove that first by undoing the nut and pulling the shaft - IF possible. Those plastic gears can strip when one of the shafts doesn't turn while the one being worked on does. Unfortunately it's more complicated when the water pump nut is also stuck and you can't remove it with a regular wrench, and you need a socket. To have access the plastic gear shaft has to come out first. It's a very delicate situation, that's why it is crucial to have it 100% immobile from the start. From the photos, the hex area on the shaft looks stripped and round, so perhaps that plastic gear already had stress. But most commonly stripping of the plastic gear would occur when actually trying to remove the water pump shaft first. The little timing chain gear on the left side is still engaged, the shaft doesn't turn but the water pump shaft does when trying to undue the nut - the plastic gear gets stripped. So, perhaps there was already some damage when the water pump shaft nut didn't come off, and it didn't take much when trying to undue the bolt on the plastic gear shaft. The water pump should turn freely, so I guess the plastic gear also already weakened. But if using an impact wrench, and the shaft suddenly turns because the wrench slips from the hex area, that can also strip the plastic gear.
Last words, if the water pump shaft nut doesn't come off, extra care has to be taken removing the plastic gear shaft. All chains should be removed, and the shaft secured solid against any possibility of turning. The hex part is best to be held by two or even three wrenches if they fit.
