I've commented in Pol's thread and I totally know what your going through. Hubby (nutbusterx) and I have just had a break up (two weeks ago) with his co-worker. Your situation mirrors ours so unbelievably its like we wrote both your thread and Pol's.
I will mention to hubby that he comment here after reading your post, he might be very helpful. He just commented to me on Friday that he is having trouble getting "stretch" (ex-gf) out of his mind and out of his thoughts...
Stretch was also mono before she met hubby and he introduced her to poly also.. But she was still manipulative.. She actually told him that it was him that introduced her to being poly and he corrected her and told her that cheating wasn't poly.. She was very manipulative and he might be able to help with this too.
That other post was my response to our situation.. It was neither clean or unemotional.. It was hard, and it still is hard..
I will have hubby respond when he can...