Mimi went and still is acting crazy. She growls, hisses, barks and spits even when none of the other cats are around. She started not only swatting at the new kitten but attacking the older cats also. I am actually afraid to leave the kitten alone in the house with her. It has only been a week, and I know I need to give it time, but I have never seen such violent behavior and frankly she is giving me the creeps.
Some cats have more trouble adjusting to newcomers than do others.
In Mimi's case, I suspect that you have a cat who is naturally hot-tempered, who feels threatened in some way by the kitten. Mimi probably thinks the kitten will take her territory in the house. Cats are very territorial. They mark their territories with scent markings, usually using the glands on their faces to mark furniture or even people. Cats will share territory to a certain extent, but they still each have their preferred spaces.