I agree that beating the heck out of yourself over this won't do you much good. At least I don't think it will. I'm confused too after reading about your ladyfriends antics. Does she know what she wants, I wonder, and maybe you wonder, too.
I was in the same position years ago, I know I've mentioned it. I could not pull myself away from the man I loved and was "sharing" him (very reluctantly) with another woman! Yes, I felt stupid as can be. Felt used, second best, humiliated horribly. Do you know how it finally ended? Well, he died of a heart attack. To this day I wonder if I would have been able to ignore him or tell him to take a hike if he hadn't died. We had plans of getting back together or so it seemed, too. I just relate to what you are going through and you can see you are not the only one who has felt so stupid.
But of course, you are not stupid! Oh the heart and chemistry of it all are so hard to resist, I still say.
I hope you will find peace in whatever happens.
CQ
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<font color=blue>"All changes, even the most longed for, have their melancholy; for what we leave behind us is a part of ourselves; we must die to one life before we can enter another." Anatole France</font color=blue>