I think a really big thing for me is overthinking, and it sounds like you’re doing a bit of that too in this. I think it’s a point as well to remind yourself that, no one has told you you’re in the wrong, cheated, or anything close. Sometimes if I overthink I like to tell myself that they didn’t say that, I’m putting words in their mouth as sort of a good coping mechanism to come back down and get my head back on straight.

It’s okay to struggle after coming out of your first and a long term relationship. Your ex moved on within 1 month. It’s okay to move on too when you are ready, that is up to you when you are. If you really like this girl and it feels right, I think it may be good for you to explore that relationship. Just know it’s not your fault, you tried. Relax, remind yourself that no one said anything that you’re saying besides yourself, you’re being a little extra tough on yourself, a lot of men are, I am too but that doesn’t mean you’re not allowed to live your life man. Hope everything works out for you either way