First of all, a bent axle doesn't affect the spinning wheel in any way, because the axle is stationary. Yes, the axle will wobble when it's spun while the wheel is stationary, but that's not an issue in the real world.
I suspect that you have a 9.5mm axle (threads often measure short because the crests are truncated), and they are available from a few sources. However, no harm will come from using this axle either as is. Or you may try to straighten a bit by mounting the cone and locknut and setting it up against the bend. Then stand in a vise and use a piece of pipe to lever it, or gently tap it home with a plastic mallet.
Either way, use the bad side to the left, so the stronger, undamaged side is on the right where stresses are higher. If you don't straighten the axle, it's orientation may slightly affect the wheel position, so mark one spot so you can always mount the wheel with that spot in the same place.