Most eggs we eat are unfertilised (battery hen eggs anyway, since there are no roosters around).
I wish I'd known this fact when I was 7, and I attempted to incubate a chicken's egg from the supermarket by carefully placing it my bed with my electric blanket on and a thermometer hanging out under my sheets. Sadly, the egg never hatched, but started to rot after a week, much to my dismay.
So I can (almost) safely say that since most eggs we buy from supermarkets are unfertilised, I can eat eggs with very little guilt, as it is simply a chicken's gamete - just a sex cell with the haploid number of chromosones, and thus cannot be considered a life.