I agree with everyone; a second yorkie is just what you, Bentley and that poor kitty need. And I would add, the sooner the better.
It took Ruby several weeks to accept Reno, at first she wouldn't even look at him. Once she determined he wasn't
ever leaving, she gave up ignoring him and found out, he was actually fun to play with. Now after a year and a half, they are inseparable.