Why?

Why? 
Why do you continuously take me down? I know I left, but I left because you were abusive. I know you weren't doing it intentionally...or rather, unknowingly, but why can't you just stop and listen to me. For years, I never felt good enough. You always wanted material things and money. Money..ugh...the ruler of men these days. I know I hurt you by leaving, but I was so easily replaced in your eyes. You already have another woman and her son and you're acting like you are all one big happy family. I'm glad that you finally found someone to make you happy - I really am. It hurts because I always wanted to be that person for you, but I guess I consistently fell short. This new girl is everything I couldn't be. Sometimes I get jealous of her, but then I think about our daughter. It killed me to see her cry when I cried or yell when we were yelling. I know the concept of "co-parenting" is ideal, but how is it going to work exactly? You never wanted to be apart of mine and the baby's life until I left. I'm glad that when I left you manned up and decided to act like a father (finally). But why...why do you have to fight for more custody? Is it because the new girlfriend thinks she's cute and wants her around more? You never bothered to care until you started dating her. Why are you trying to take the only one that matters, away from me? Yes, she is our daughter, but after everything - why are you still trying to destroy me? You know that she is in better care when she is with me. I make sure she has everything she needs. You say you want to be her father and you are, even with our current custody agreement. You pushed for this agreement and now you are asking for even more?! I just want what is best for our daughter and the constant going back and forth, just isn't.
Idk what to think or say anymore. Although being in an abusive relationship is never a good thing - neither is this. Did I make a mistake by leaving? Should I just stayed and dealt with it? At least then she would have one place to call home.