My first thought is to tell you to move on. If she's dating a guy like you described and taking his shit. She's got much bigger issues than you realize...deep seeded issues.
I would take this as a hint and move on because she sounds like she'll give you hell. Or worse...you start dating her and then she breaks up with you because you don't bring enough drama like her ex. Some girls feed on that.
That said, my friend Jason King wrote a really good ebook on this subject exactly and you might be interested in checking it out here:
http://bit.ly/friendtolover
Just to give you full disclosure, if you like that link and buy from it, it's an affilate link and I get paid a tiny %. But I don't want you to think I just gave that to you for this reason. It really is a good book and I think you'd like it....may solve your problem pretty quickly.