When I was 5, we had a dog like that. I couldn't be in the same room when he was eating, or he'd try to bite me. He finally did one day, I got 7 stitches for it. My dad had him put down before I even got home from the doctor. A few months later, we got a Collie, best dog I could've had growing up. You made the right choice, in an extremely difficult situation.