Ok. Here's my thoughts.
In a nutshell, they haven't changed.
The expanded "remix":
Your love for her is hurting you AND is hurting her. Even if you are 100% wrong, the fact that your reality and her reality can differ that much means that you will NEVER be able to mesh without anything less than a profound breaking and remolding of your mind or hers which I can tell you from personal experience is just as fun as it sounds.
I do not know if you are right or if she is right. It does not matter who is right. Either scenario ends exactly the same way. You need to find a qualified mental health professional, hopefully one that knows about poly and get help. Tell them honestly what you are feeling. See the professional WITHOUT your SO there and maybe later you will have a joint session if you haven't broken up with her.
If you do not do this there is a very good chance she will continue to hurt you and you will continue to hurt her(and make no mistake, you are hurting her).