Lisa-
Did you ever stop to think that maybe Leila WANTS to be an only child? She may just stop all her bad habits once she becomes the only cat.

Is there someone at work that you know that will take her on at test/possible keep type basis?

We know that she is a loving kitty (runs to sleep with you) but she just might be the type of cat that doesn't get along with ANY cat or animal.

I would try re-homeing her before putting her out. I too will look around for you, but you already know my connections