We for several years have had a pair of lovely bantams. Last week our dog got into their house (through a whole range of circumstances) and killed one of them. I'm now not sure what to do with the remaining one- apart from making sure that the dog can not get near her. If I rehome her - I have a friend who has a few chickens and ducks and may be able to take her- will she get picked on as the new girl in a group? Or if I keep her here alone will she be miserable? I don't feel up to getting new chickens as we are still a bit shellshocked after our dog's attack. Our bantam is about 4 years old and still laying, though not every day.
I know you're not ready yet, but why deny yourselves the pleasure of watching your hens and eating their eggs, do get another one. If you don't you will always have a bad memory, but if you do get another bantie - in time you would get over the bad memories and replace them with new nice ones I doubt you will let the dog anywhere near them again! However as the dog v chickens would always be a worry, you could perhaps put a double door on your hen run, so accidents would be far less likely to happen, or, even get a dog behaviourist in - its a fascinating experience if you can afford it, you will learn lots, and it will solve the problem.
Chickens don't like being on their own, they're social creatures. If you rehome, so long as your friend introduces them properly, she should be fine but I'd imagine she would be bottom of the pecking order.