Should I let him go

So I found the man I was supposed to marry, “A”. But due to a very long and complicated story I ended up back with my baby daddy, I felt like it was the best choice for my family. So I obviously ended things with “A” but I can’t stop wondering if I should have been stronger and stuck it out with “A”, he was such a good man. He treated me like a goddess and loved my baby like his own and I know I would have had an extremely healthy relationship for my daughter to witness as well. I don’t want her to end up with a man like her dad. I know I destroyed “A” when I ended things with him, he had unconditional love for me. But now I feel like he will never forgive me. But lately I think I finally feel strong enough to leave my baby daddy for good, I know I deserve better and like I mentioned above, I want my daughter to have a healthy family life so she can have a strong, stable mindset growing up and I feel like she will not have that with her dad in the house. But on the other hand, I’m scared to leave him because I worry how he will treat her when he’s by himself and overwhelmed. He’s impatient and can be mean sometimes to his older daughter, she’s 5, and even to my daughter who is less than a year. Very impatient with her too. But when I step in for 99% of the work with both girls and the entire household chore list, he’s a great dad. If I left my baby daddy and reached out to “A”, do you think there’s a chance he would forgive me for going back to my baby daddy? He truly didn’t want me to and made me promise not to go back to him because he knew how he was to me in our relationship. But in the end I felt like it was the best thing for me to do. I regret this now, but for selfish reasons. Should I forget the idea of the man I was supposed to marry? It’s been 1.5 years but I still think about him. He’s probably happier without me anyways.