You didn't just cross thread the pedals, you completely jammed in thread that are turned the opposite way LH vs RH and RH vs LH.
The pedal spindle is steel and much harder that most crank arms which are aluminum so if you put them in all the way, you destroyed most of the threads in the crank arms.
I would advise against trying to clean them up and put the pedals in. Too much material is missing and one day when you hit a bump hard, it is likely your pedal is just going to fall out and you'll take a tumble or plant you crotch on the top tube.

Most of us don't consider that a good way to save a few $$, but it's up to you.