You should be able to cut the hinges loose and straighten the door with a jack and chain. Also you could put the rest of the door strapping on, cut the hinges off, install a gasket around the door flanges and weld the hinges back in place.
It sucks to undo work, but you can cut those bullet hinges off and reuse them. I would really recommend you do that whether you bend it back or you put flanges all around and use gaskets. My bet is flanges/gaskets will get you 90% there.