Coparenting.. dos and donts

I just need some encouragement. I am so drained and worn and honestly, depressed. My child’s father and I split up a year ago. Right after he was born and unexpectedly. Custody is 50/50 and we live within five minutes of each other. I was in love with his dad, and we were together for a few years. He broke up with me randomly, was on tinder within a few days. I figured eventually he’d realized how stupid he is for splitting his family up. The worst thing thar could’ve happened is we argued and needed to communicate better. No infidelity or abuse or anything major. So I’ve just been so damn angry at him and this resentment still hasn’t gone away. I’ve dated other people. Worked on myself, lost 30+ pounds. Focused on school and my career. The hatred just hasn’t left me at all. I just can’t understand why anyone would want to raise their child this way unless something serious happened. I even asked if he ever loved me, expecting he’d say no, because then I’d understand a lot better. Nope. Apparently he did. So I just don’t get it whatsoever. I never will and I never will get closure. I’ve even been into therapy. I don’t know what to do anymore. I don’t want to hate my child’s dad. I want us to be friends or to get along because it’s the right thing to do. But pretending like he’s a stranger is the only thing that helps me. When we exchange our son, I avoid looking in his eyes, I say the basics like when he last ate and napped etc. It hurts because it’d be nice to have a stronger relationship than that but I just can’t do it. I’ve tried and I feel bad for letting my emotions get in the way of this. Can anyone relate? Like how long is this going to last? I grew up with divorced parents and it took them 11 years to even be in the same room together :(