Conflicted

Context: my neighbor had a Yorkshire terrier that was a little shit. She would toss him in the backyard, I live in a condo so it’s only ten feet away, where he would bark for hours on end. He’s tried to attack me and my dog multiple times; I’ve always been afraid that my dog will protect me, but he’s a Staffordshire mix so they tend to be put down no matter what happens. Her dog ran up to mine last week and tried to take a chunk out of his nose.
Anyways, she let her dog out this morning but her gate was open; apparently he made a dash for it but she didn’t really look for him and went to class instead. Fast forward a few hours and she found him on the side of the road. I feel terrible but not at the same time :/