You sure we don't know the same gal? heheh, sounds very similar to my hearts most recent fall. She's the friend of my best friend and is uber sweet, caring, just one of the most wonderful ladies I've had the pleasure to meet, only thing is she is mono. Oh, and shes also not bi, so even if i could get her past the poly thing, she'd never be mine.
Met her about 6 years ago, shes been in my life since. Only thing I can say is though my heart lurches a little when I'm around her now, its not the full upheaval it used to be. There was a time right after I met her when I wouldve given her the world for just a smile, now I keep reminding myself its no use and I only allow myself to do little things for her. I also don't see her as often as I used to. Its not a great situation, but it lets my heart calm down and loosen the hold it tries to have on her.
(((((((Hugs))))))) Good luck to you. Though we can't choose whom our heart falls for, we can try to make it see reason when its simply not within our grasp. I do still love her, but its more a friendly love now as its less painful.