Years ago a friend of mine had to have her aggressive pit put down. She paid a trainer thousands in an attempt to control him but I strongly question the methods of the trainer. She and her boyfriend broke up and he left the dog with her. The dog challenged my friend's dominance all the time. She was scared of him. One night she moved her foot in her sleep and he bit her foot. He also bit the tip of a finger off, a small chunk of flesh from the top. She knew it was going to be her or the dog. And if not her, god forbid if the dog ever made contact with anyone or anything else. I stopped visiting her because I had never seen a dog's jaw quiver and it want to shred me apart so bad. It was a frightening animal that she had to put away for company.
She had to have him put down. I remember her guilt because the day of his death, he was so well behaved, she said. Very happy and listening to commands, doing everything he was told, including hopping right on the table for euthanasia. She felt tremendous pain having to do it, but he was a dangerous, strong dog that wanted to kill. Unfortunately, its just a sad situation.
Please don't beat yourself up. You took responsibility. You protected him, too, from biting someone, being confiscated, and put down by the state. I get that you resent the other pets right now. Your other pets brought you joy, too, that's why you have them- you are temporarily numb and will love them again. Its not their fault your dog became increasingly aggressive, and with time those feelings will subside. I know its never easy to go through an ordeal like this. They needed you to protect them, yourself, and other people's beloved pets as well, and you did, because dee down you knew that was what you had to do.
As a child, my mother had an aggressive dog put down as well. He was a cocker spaniel mix. He bit and snapped at the kids and other dogs, and when my mother went away for a week, he tore apart the brand new sofa that they had just bought. She did put him down and I was haunted by it and dreamed about him all the time. As kids we didn't go to the euthanasia- we just came home from school and he was gone. It was surreal and disturbing for him to just be gone, but he bit people, and my mother is normally an animal lover that sometimes seems to put pets over people but she knew to put him down.
I'm so sorry for your pain. I know you miss your friend. (((hugs)))