dlt1, good to hear that you got an C appointment so soon. Bring it all out there! get it out of your system and go on!
As far as dealing your confronting issues, you sound like you are doing a great job in that area. I, on the other hand was never one to back down, I stood up for myself, and my loved ones, all of my life, so now learning when to stand and when to back down/calm down, is a 180 for me.
Sounds like you have quite a test ahead of you, with you now being your ex-GF's boss. Mind if I ask you, did that R, end on a good note? If so, maybe it won't be that hard to deal with her. And maybe, through the grapevine, your W, might hear about you and her starting to get rather close, might even make your W a little jealous, which believe it or not can be a good thing, as Strange once told me. I think he read an article on it. When you get the chance you might ask him about it. Take care.