Vince - If you don't like the person you are when you are with her, that's a big sign it's time to go.
In a perfect world people would act perfectly, no matter the provocation. Reality is, there are people who can say and do things that drive us to act out of character. Crazy makers. Now I don't really know how much is you vs. her, but I suspect you are both somewhat enjoying the sick interactions and that is unhealthy.
If you think counselling will help, then by all means go. But it is my long experience that people really don't change on core behaviours like these. Your GF is a broken-winged bird. She needs to learn new responses and habits that can probably really only come with therapy and, a lot of introspection. Your personalities are keeping her from doing what's needful, I'd say.
In your case, I think you've done your work. Now your task is to find someone who brings out the best in you, doesn't stomp all over your own insecurities and generally makes you feel like the awesome guy you are. She's not able to do that, V. You know this.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh