I have experience with a fear aggressive GSD. I rescued him when he was a year old. He was great with us, but couldn't be around strangers as he would bite. Luckily, we seldom have visitors and when we would, he would be put in a bedroom or on a leash until they left. When we had him in public, he was fine as long as no one tried to pet him, so we keep everyone away. We would never give him up, we learned to live with him and know what he is comfortable with and what he is not. When he goes to the vet, he is muzzled. I think the best thing for you to do is to neuter your boy and give him to someone that can handle him. Good luck.
Bridgette- 05/93-09/10, Jasmine-01/96-5/06/09, Dakotah-14/12/05, Joshua-31/10/12, Sabrina-1/07/01-26/11/13, Shane 11/09/01-08/22/14, Samantha-07/12/14, Amber, Jody, Wendy, Gabriele-01/23/12-12/21/13, Kimi, Jakob, Mandy, Abigail, Tanner, Tonya.