Yeah, be civil and talk to her, but just talk to her like you would any other person. When you find yourself going out of your way to be extra-something because it's her, hold back. After a while she'll get bored of wondering what's going on with you and leave you alone. Then when you're alone other girls will notice you instead of you being stuck in her shadow, and from there it only gets better :)
Also she will probably hate the next couple people you date thus giving you justification for your actions (because although you were civil, you might feel bad for holding back)