I’m going to come in here for some tough love. We do not have the full story, we don’t know the whole dynamic, and we never will. So to that end, I’m not going to pretend to know what advice to give you on communication with her.
What I will give my advice on is that your posts, I didn’t read them all, stand out to me in two ways. 1. They are frantic, anxious, and clearly (as you’ve said yourself) emotionally unstable. 2. There’s a lot of me, me, me. Frankly, they read very selfish. As long as you are in this headspace, you won’t solve anything with her. Gym and friends are great, but this needs some real soul searching and mindfulness work. Keep talking to people, keep your body healthy, but get your mind healthy by going to individual therapy.
From a personal standpoint, I grew to hate my ex while I was pregnant, I hated him even more when my son was born. Hormones can make your patience run out and alter how you see someone, but I’m also a big believer that I grew to hate my ex while I was pregnant because I was protecting my baby. My ex was a psychopathic narcissistic and still is. He has never put in the work to be a better person, partner, or father. So if you want to have a good relationship to your child’s mom, which may not end up returning to romantic, and with your child then you have to fix your relationship to yourself first. Be the best dad you can be. Because I have always told everyone I wish that my ex would one day get help and be a good dad. There was a long period of time after our breakup that, if he had truly changed and done whatever work he needed, I would have considered getting back together.
Just my two cents as someone who hated their partner and ending the relationship asa result.