It's difficult for me to tell exactly, but I think that may just be the sort of material that can occassionally be enclosed in an egg from a bit of tearing of the hen's reproductive tract as the egg passes along before the shell forms around it. I believe in a viable egg there would have been more actual fresh blood. This looks somewhat more brownish, (like the material I mention above does in an egg), to me than the actual embyros I've seen. I have accidentally cracked them open in a frying pan not realizing that I had missed collecting one for a few days and you can see the developing chick moving about rather like a little heart beating. (Not a fun experience at all and I felt terrible!) I have dropped a fertile, developing egg and it started to seep bleed immediately when it hit the ground.
I think you should not feel so bad - it doesn't look like a living embryo to me.