i had a German Sheppard once long ago. she was a beautiful dog but not very bright. She pulled at times and I found a halti very handy is reducing this a bit. I can see you are in a very difficult situation, They are such a big strong breed but loving and loyal. However I think you do need to consider your own welfare too.
Should you decide to re home - I hear that the Dogs Trust never put a healthy dog to sleep. There’s also the blue cross to consider and I should imagine there’s a German Sheppard rescue somewhere that would specialise in re homing the breed with people familiar with it. I think, depending on age and character sometimes the police are interested in recruiting big dogs.
Wishing you the very best of luck with your quest. Your dog is very lucky to have finally landed with such a responsible owner. Daffy