I’m so sorry this has happened It’s always hard making these decisions, but a human aggressive dog with children at home is just a disaster waiting to happen, especially given that he’s been growling at them too.
A secure run is a possible solution, as long as he’s kept on lead when you’re walking him, but you’d need to make sure he couldn’t grab anyone near the fence since that seems to trigger him. I’m also not sure what his quality of life would be, but it’s an option if you don’t want him put down. Hope your neighbor is ok.