Completely apart from whether you should go back to your ex or not, I was really struck by the number of passive voice references you made to your own actions in this description. You say “resentment occurred” instead of “I was resentful.” You say “Distance was difficult” instead of “I had difficulty with the distance.”
It’s possible to construe this as just a writing device, but I think it’s worth looking at. Where is your agency here? Things don’t just happen to you. Your life doesn’t just “become” things, and you aren’t just a passive witness to events. What role did you play in these things? In the development of “Strong crush feelings” – who did they develop in? You? THe other person? Where is your agency?
Whatever happens, it does seem that one of the things you could work on in therapy is greater comfort making decisions, owning them, and accepting accountability for them, good or bad. It might be that you’ve made a mistake, but you’re entitled to make mistakes – you’re entitled to feel things, make decisions based on those feelings, and even experience regret when your decisions don’t bring you the satisfaction you thought they would. You’re even entitled to renege if you think that’s truer to who you are – to say “This whole thing was a mistake, I want to stop and start over in a new direction.”
It might be this is just a verbal tic that helped you in writing the description, but please do consider whether it reflects a broader thought pattern in which you are watching the world pass you by, and you don’t feel responsible for or accountable for or participant in the things that happen to you. You are. You’re steering the ship – you might fuck up, you might not, but you are making the decisions, and it’s OK to do so, even if they only seem right just now and later on you realize they were wrong. Take some agency; recognize you’re the decider, as it were.
I had a great therapist once, in a similar situation, and his advice was “put both feet in.” He told me “You’re trying to keep one foot in the safe world where you really don’t take your decisions seriously, and one foot in the world where you really commit and go forward. It’s not fair to your partner to have one foot in and one foot out. Whatever you decide, put both feet in.” You can retract a foot later. But while you’re in something – please be in it, for real.