Awesome advice everyone..I let my male cat go outside and my girl kitty goes crazy! "Where is he" she will sit at the window meowing and looking for him. Best of luck..I hope you can get your other cat back. They both are probably suffering.
I agree with the first two posters. Shes probably very lonely and depressed. And it would be best to have her old friend back. But if that isnt possible, I think she would really enjoy having a new cat around. They are very social creatures and need someone to be with. If you dont do something, she may end up with some behavioral problems in the future. Give her a hug for me.
I agree with margy. First, ask for the male back, and offer to provide your ex a new kitten if he would like. If that doesn't work, get a new cat, from the shelter is a good idea. Slightly younger than your female, and a male, might work best.
Have you asked him if you can have the male back, if not what about another one from the shelter .I bet shes horribly lonely and depressed .