<human>: Can you condense the text into a few key points?

GF and I have been together over two years (lived together almost as long), but she is still hung up on her ex. She and her ex had been together off and on for five years. Her ex left her for other people multiple times and then came running back when those relationships didn't work out. She left her in some really fucking awful situations but my gf always took her back. 

When we first got together she almost left to go back to her ex a few times. And nearly left for someone else once as well. She has promised me (time and time again) that she is over her ex now and that she doesn't need to live in the past because she has me and I am everything she has ever wanted.

Cut to tonight, I find an email that she has sent to her ex. She tells her how she was trying to get back to the person she used to be, the one her ex fell in love with but that she took too long to find her. She kept asking if the ex was happy with her new gf, I guess she is hoping that she will say no and she can go back. I haven't said anything to my gf yet because I know it's just going to result in her getting upset with me because I looked at her email. We will fight about it, go without talking for a bit and then I will apologize...how it always goes.

I never believed anyone would ever love me and I guess I was right. I feel stupid, like I am being used. I don't want to admit failure (if that's what this is). I just wanna disappear/die. What the fuck am I supposed to do?
<bot>: Longtime livein gf is still hung up on her ex and secretly staying in touch and basically begging her to still love her. Don't know what the fuck to do.