Not to crush your hopes or anything, but a couple of big warning flags here.
One, she could be momentarily getting back at her longtime boyfriend, and you're the tool for that.
Two, even if she is coming off her last boyfriend and you're safe and familiar to her for the transition, chances are that anything with you at best would be a transition for her.
Not to kill your dreams there, but I'm just telling you to keep a level head. I know of too many guys in this scenario in the past and one of those two things was the only outcome.