When my ex left for OW, I figured it was all me. I said "what could I have done differently to make him happy and not cheat and stay? Then he went on to marry the other woman. They have been married longer than we were and together for the same amount of time we were. So, I asked myself "what did she have that I don't?
I know exactly what it was. The person he wanted me was not the person I wanted to be. I sustained being the person he wanted me to be for 9 years until I could not anymore.
What is important is not who you are to him. it's who you are to yourself. That you are the person you want to be.
I know you would like a quick fix. I get it. But there is none, and you are doing just fine, I don't think you could do anything differently. This is his issue now yours.
As far as your father, it really is a catch 22. from the outside it is reasonable to see that it is insanity to take back a guy who walk out on the mother of his child when their baby is born. My dad did not take kindly and still does not to this day. Looking back, for me, I was just desperate to keep my brand new family together. But I knew a man who did that to me and my child is not the man I wanted as my husband.
He is being selfish right now doing what he wants when he wants and is considering no one else right now. You didn't drive him to that. he is choosing to evade his reposnibilities. And you can't make him, no matter what you do differently or perfectly. he has to make the decision himself.