I'm really sorry it seems that you ended up with these. Some people do because the signs will say something like Cornish Cross, but not have "meat bird" or "broiler" or any specific wording that tells unfamiliar people what their purpose is.
Some people will try to keep them as pets by limiting food intake or whatever. That's a personal choice, of course. I feel that it is inhumane to try to raise a meat bird beyond the recommended slaughter age. They get too big and can have some major health problems that cause then pain and leave them with no quality of life until they ultimately die. Not saying don't try if you feel that you want to, this is just my personal opinion.
It's understandable if you wouldn't want to process them, but you could probably give them to someone who will do it humanely and would use them for food for their family.
Again, I'm really sorry, and I hope you're able to make the best decision for yourself and the birds.