Okay, short version: I (f23) was left by my ex (f21) last year, but we've been living together as roommate cuz of university. She left me and started texting a guy from the other side of the country. I was jealous for a year, but yesterday, after she admitted to not having any kind of interest for sex with women, I realized that I don't want to still have a relationship with her. She told me that, while she loved me deeply, there was always something missing and that she had a block towards sex. This didn't mean that we hadn't had sex and that she didn't enjoy or sought after it, just that she had a physical problem with it. And I realized that, even tho I still love her a lot, I don't want to have a relationship with her. I don't want to leave her in a relationship that is not totally fulfilling, even if she'd think I'm the love of her life.
Moreover, right now we argue a lot because of my jealousy and paranoia. We're almost not even friends anymore and when she has problem, she goes to other for comfort. I know that this is normal between friends, but we got from "i know everything about you" to this. And I get insecure.
And it's not that I need a relationship or that I'll just start online dating or whatever. I just realized that I don't have to feel guilty if I find someone attractive. 
I'm just scared I'll forget about her. She's not just my ex. She's not just my fp. She's everything I have. 
And this is toxic. Because more than once we argued so much that she wanted to leave. She told me she was depressed because of me. But I want to get better and I'm going to start therapy in ten days. And I want her to be happy and to be by my side forever. I don't care if we're not together anymore. Yes, I still love her and I'll probably never find someone as good as her because I belive in soul mates. But life is not that easy. I believe that we were made for each other and here we are. We have just so much stress that out bond can sustain. 
And I also said short version, but here I am rambling. I just want her to be happy. I really do. I've been feeling so terrible this past few weeks because I've seen her so depressed and I know that's also my fault because she felt trapped (she left for a month to study abroad and once she came back I was more clingy than before, like I jumped months back in my mind), but I feel so terrible seeing her not being truly happy. I just want to see her smile everyday, I don't care if it's because of someone else. I love her so much that I don't care if she doesn't love me in that sense anymore... 
This was just to say that I could have another relationship without the guilt and it ended in me rambling because of her. Like always ahah