What happens in animal shelters?

i have 5 cats living in my house since my one cat got pregnant.. the problem now is that they are starting to become a problem because of the mess they do everywhere around the house so i was thinking about giving them to a animal shelter, but i heard that they do bad things to them in shelters so i'm worried i don't want to hurt any of them i Just can't have them in my house any longer..so can someone tell me if animal shelters really do hurt the animals and if they do then does anyone have a solution as to what i can do to get them out of my house but in a safe place... if Animal shelters don't harm animals then does anyone know of a good shelter in virgina ...thanx in advance