A person who likes to act incredibly bitchy, but can't handle bitchiness in return and gets disproportionately hurt feelings. Usually demonstrated in the interwebz, as one-way bitches rarely have the balls to demonstrate bitchy behavior to anyone's face.
Tiffany: Did you see what Sparrow said in the blog comments?!
Augusta: Yeah, but as soon as you give it back she gets all emotional.
Tiffany: She's a one-way bitch.