Ignoring may come off as butthurt, but who really cares what she thinks. If you're not interested in dealing with her anymore, then ignore her forever.
So she goes back to the ex. Inevitably it goes south, as it usually does when exes get back together, and now she reaches out to see if you're still available? That's what it sounds like, why would she be reaching out after a year if things are going so well with him? If her IL was high for this guy you wouldn't even be a blip on her radar. If you do speak to her, I'd just say something alone the lines of "I'm doing great, thanks". If she keeps contacting you let her chase a bit. Seems like you already know what her game is, so you need to decide if you're going to play along. I remember a corey wayne vid on this...I'll see if I can find it. But in it he says the better it's going with the current BF the less you're going to hear from her. The worse it's going the more you're going to hear from her.