I'm so sorry. Please don't be down on yourself. You have to put Nakita first and know that Phoenix will find a good home.

I've been there with a similar situation. Ripley was my first and only cat for 10 years and when I finally decided he was old and mellow enough to handle another cat I decided to try an adult. She was awesome. Her name was Mystic but because my husband didn't hear me correctly he thought I said Sticks so we called her that. We had her for over three weeks but it didn't work out because she became very dominant over Ripley and my dog Disney and started peeing in their beds and eventually our bed. After having her checked for infection or crystals and she was clean we tried to work with her more but she smacked my dog and cut her nose open. My dog was only sleeping in her bed. It broke my heart but I had to return her to the rescue. I still feel an empty sad feeling when I think about her but I know she was adopted a few weeks later as an only cat and was very happy.