+1, let a local shop retap or chase the BB threads. If you have a steel cup with the correct thread, you can make your own chaser by grinding grooves across the threads (like tap flutes) for chip clearance, and running it into the shell to clean out the remains of the old cups. Ince the threads are clean you can install new BB cups. Hopefully you can get a left one without buying a pair.
For future reference, grease BB threads before installing cups and don't force a BB cup in, it'll be hard enough to get out later as is.
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