I'm not comfortable with the friend thing, either. I have always been in awe of how you get along with her, to begin with.
It's like, if he stays an a$$, then it is easier to think, ok, this guy changed and I don't want to be with who he has become. It makes more sense to the wounded heart.
If he is nice, it is too easy for the feelings of attraction to come back. Then I look to blame myself again, since such a nice guy wouldn't have done these terrible things if only I had (fill in the blank). It also feels like I am "letting him off the hook" when he gets to act nicely to me, like pretending that nothing bad happened. Both very bad DBing...
Hope you feel better soon - I'm right there with you, suckish summer cold...