Tough luck RR, I once fired by radar on friendly merchant, luckily it didnt sink.Since that I wait until the storm passes, just shadow the convoy then attack once its cleared up.Takes time but better than risking it.
I once sank a Russian merchant right outside Le Perouse Strait at night.Was dark but couldnt see the flag, crew identified the ship as an Akita Maru(Ducimus forgot to change the name of that freighter when on the russian roster) so I let loose some Mark 23's. The fire illuminated the Russian flag, not good.So I continued to patrol the Sea of Okhotsk and sank some more ships, finally a DD got lucky and nailed me when one lucky depth charge, that was the end.
As far as starting over, you should just leave it at that, had a great career and made one huge mistake.Start a new career and learn from it.