I see similarities between my situation and yours in some ways, although the end game for me is somewhat different (read my thread). However, she may very well be trying to make you angry and end it yourself, because she feels guilty doing it to you (which means she cares about you). In my case, my husband sometimes says I can have a divorce if I want, not because he necessarily wants one, but I think he needs to hear me say I don't want one as otherwise he feels guilty about what he is doing (which means he cares). I think they are actually feeling a lot of anger at their own feelings but they take it out on us. Remember the saying, "Don't believe anything they say." I try to look at the things he says and see if there is another reason he might be saying it other than taking it at face value, and sometimes it actually makes more sense that way.
Focus on the positives she has said about you-that you are her best friend, that she is happy you are working out. Keep these things up. Yes, you want all or nothing, in or out, that's totally understandable. But I think it is better for the time being to say I'll accept less than all as long as we are still married, but if it ends in divorce then it's nothing. That gives her the space to work on what she needs to work on but at least lets her know the serious consequences of ending it.
