I understand how devastated you feel. This has happened to me. Several years ago, a bobcat figured out how to open the gate to the covered run, and it appeared I had no chickens left. The attack scattered the flock, and over the next 24 hours, I found alive all but the one hen, my favorite, darn it, who had been eaten.
Have you searched thoroughly for any survivors? When a predator attacks, chickens scatter in panic, ending up hiding in the most unexpected places. Search under wood piles, up high in trees, behind porch and deck furniture, in out of the way nooks and crannies. Chickens will sometimes spend two days in hiding, fearful of coming out in case the predator is still lurking.
I've given this advice on this forum before, and had the OP come back and report they discovered several survivors hiding up in trees. Recently I took my own advice and went hunting for a young pullet that I was sure had been nabbed by a hawk. I found her safely hidden between two straw bales far from where the attack took place. A few years before that, a hawk killed one of my hens, and I couldn't find the rest of the dozen chickens I had at that time. I eventually located all but four small chicks. I was sure they had been eaten. Hours later, as I was talking on the phone out on the front porch, I heard a slight noise behind me. There were the four chicks, snugged up between the house and a wood barrel. No telling how long they would have remained there silent and still if I hadn't discovered them.