How do you know if you don't love someone any more? I asked myself that same question a few years back with my sons dad. Whenever we were affectionate it just felt empty. I felt empty. I cared about him but it just didn't feel right any more. He'd never done anything wrong, nothing to trigger these feelings off, I think we just grew apart. Or I grew apart from him. I was very young when we met (16) and think I changed a lot over those 11 years. What I decided to do was to have a break from us. He stayed first with a friend then with his mum. I realised that I was happier with us apart and that made my decision for me so we split permanently. He didn't want that and I felt awful because I was hurting him, but it was the right thing to do. That's how I answered that question for myself. Maybe some time apart would bring some clarity to you? I can relate to your feelings on what she did, my husband now did similar and I was devastated. Emails and naked pictures to some random woman, I too was ready to walk but I do really love him and believe it was a terrible mistake on his part. It's not easy working through it, and I feel so much rage towards him at times, but what we have is worth fighting for. I know in my gut if I ended things with him it would be the biggest mistake of my life because I'd be letting someone I truly love go and I don't think that's worth it over one mistake. Trust is a hard thing to rebuild, but it can be done. If I were in your shoes, I'd take a break from her and see how I felt. If it felt wrong then maybe I'd know we had a good thing worth working on, if not, then I'd end things for good and work on myself and finding true happiness with someone once I felt more stable.
I think the only way to know your true feelings for her is to take her out of the equation for a while because you sound smothered by conflicting feelings both about her and yourself. Don't doubt your strengths, I think a lot of the time people doubt they'll manage on their own because having someone around is what they're used to. It is scary at first, change isn't always easy, but it could serve you well. It could also bring newfound confidence and strength within you which I think is important in any relationship too. Independence, knowing you can rely on yourself. Don't stick with someone who makes you miserable, but be sure you're not throwing away something that may just need a little work. Test the water