We're going to try taking it slower, going back to letting Munchkin only see the kitten in a laundry basket. I don't know if that is going to help when she spent quite a while today just sitting outside my office (where the kitten was), hissing and growling at the closed door. When she's responding that violently to that little interaction (i.e., only the smell and occasional sound of the kitten), I'm not sure what to do.
I'm a mix of emotions about this, because I feel sorry for Munchkin and concerned about her happiness, but I also feel impatient with her. I want her to just get over this and be reasonably okay with the kitten. I know she can't help it, though.