My dog killed a Cat. . .

[chocodilly]

I feel honestly terrible and I can't stop crying I have had my dog for three years and he has never done anything like this. I just moved to a new house and there are holes in our fence that our dog escaped out of. He likes to chase small mammals, but I dont know he had ever caught one before. My neighbors (who owned the cat) are obviously heartbroken and terrified. He is great around children and has never shown aggression towards a human. I know there is no way I can make them feel safe. I am the new neighbor here and now I know i am not wanted. What do i do?