dog killed cat

We have a fenced in area for our dogs. I let them out a bit ago. And then I got a message from my neightbor freaking out that they killed a cat. And she was crying and I ran outside to figure out how they got out and one of the panels fell down. I got them back over and out the panel back up. I messaged her back asking if there's anything I can do and I'm so incredically sorry I don't even know what to say. She still seemed upset and I'd imagine so. But I didn't say much more I just threw them inside. I don't know what happened to the cat. They're still at their house, so they didn't do anything about it. I believe it was a stray because she gets a lot of strays where their house is at. She also told my boyfriend and he called me and was all pissed off saying I need to pay attention more and that was probably someone's pet and cops might get called now. (I was paying attention I had just let them out they go back behind the garage a lot where I can't see them so I assume their there) What do I do? I feel absolutely horrible and worried for my dogs if something happens to them now for doing that. I also found out a few days ago I'm pregnant so now I'm scared I'll stress to much and somethings going to happen to the baby.