Should I put my dog to sleep for aggression?

I adopted a doberman from a rescue. The rescue had issues with honesty and didn't let me know that the original owner gave the dog away because it bit her autistic son. She is a doberman and seems to just be "wired" wrong. She will flip out over every little thing. Just now I tried to correct her for leaving the property and she tried to attack me. Snarling, growling, attack me. Earlier today I tried to get her to stop chewing at her side and my vet suggested an E collar. She punctured my hand in the process. Now it may seem that things trigger it, but at random times I will be sitting at my computer or doing dishes or petting her and she will attack me. I have had her to vets and behaviorists and nobody can help her. Nothing medically is wrong. The rescue I got her from has a lot of issues with the law now, they even lied to me about her breed. They told me she was a pointer but she was a doberman. She was so emaciated when I picked her up that I couldn't tell the difference. It may come across that there is a dominance thing here, but outside of the aggression she is very loyal to me. Walks beside me on the leash, sleeps on the floor next to me. She has snapped at 2 of the neighbor kids and then I said "no more" and wouldn't allow them to pet her. She has snapped at my little niece and the worst part is even if I wanted to muzzle her, she wouldn't let me. I have tried and she again attacks me. When I take her to the vets we have to sedate her so she doesn't bite anyone. I live alone and I love her to death, but I cannot live in a prison anymore, never knowing when I'm going to get hurt. Would it be best just to end it? I feel so horrible that I failed her. But I myself have PTSD and it's literally very traumatizing to have a dog walking around your home who may attack at any moment. It's even more traumatizing when she does.