No big deal. What you need to replace is not the vlve stem, but the valve stem core. This is a 30 second job.
Directly below the piece you bent is a threaded section that looks like it is part of the valce stem. It's not. It has wrench flats on 2 sides. Using a small crescent wrench, valve-stem tool, or (carefully!) pliars, grasp the wrench flats and turn anti-clockwise. It will twist out.
Replace it with another (available at a good bike store.)
If you use valve extenders, now is a good opportunity to do that job the right way, and add a valve-stem extender to your tire (Tufo makes nice ones in 2 sizes.)
MH
Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
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