Well first of all, fuck all and every single one who shuts down a human being trying to find a solution to a problem that is fucking up his life, even if for you the solution is quick & easy. Not saying someone did or did not, but once I felt like that here and it was horrible to talk about your life for an advice and have 11 replys of "attention whore".
Anyways, after loving a girl, losing my virginity with her, being faithful to her, go trough 3 months in a relationship where a good amount of people around me knew she was being unfaithful and no one cared to told me, to try to forgive her, sex without feelings and shits like that, the only thing I could ever advice you is fight for what you think is right and for what you think it should be done.
But, remember that one thing is to "fall in love" with someone and another thing is to love someone. If you are sure you haven't counfused these, do what you think is the best for her and you're able to do, or it isn't love.
Hope my "maybe fucked up" point of view helps you in some way Mcdreary.