I feel horrible, help ? D:?

I had four kittens, and two were killed by a dog in our neighborhood. I decided that even though i bottlefed them from the first week of birth it was best to get them a new home. I know this sounds silly, but i feel like they will think i didn't care about them. I don't want them to die, they're such sweet little babies. Im leaving for vacation today for six days and i won't see them again if they are adopted before i'm back. I feel so horrible ):