How to get over an ex who randomly stopped caring

Me and my ex have a 10 month old together. He’s broken up with me a few times since he’s been born. Everytime he leaves he says he doesn’t love me or care and a lot of awful things like he wished he never met me but he eventually comes back and takes it all back and in October after he was gone for a month, he told me he missed me and wanted to try to be together again and that he’d change and i hesitantly let him come back. February first he left me in the middle of the night. He packed his stuff and was gone. The night before he left he was telling me he loved me and how things were changing then he’s just gone when i wake up. We’ve been going on dates and everything was okay for the most part, then he’s just randomly gone with no explanation. He was buying me stuff and saying he loved me and everything. When i asked him why he left he just said he doesn’t have to have a reason, and hangs up in my face or he just screams at me. I have a heart condition and anxiety and i told him when he texts me to talk shit it just makes my heart rate go to almost 200 and i can’t eat or sleep because my nerves are soooo bad. I asked him to stop texting me and then last night he texted me and said “don’t bring any guys around our son” and i was like what guy, then he was like “oh I’m sure you’re talking to guys now and have a new man” and he unblocked me on Facebook. Ever since then I’ve been a mess and my anxiety is so bad and i keep thinking of things that could be wrong with me, like why he left. Because i don’t know why and i miss him and he doesn’t care about my mental or physical health and i don’t know how you can do this to someone you supposedly loved less then 3 weeks ago. It just hurts, i feel like I’m nothing. Like i don’t matter to him and never did and i was lied to for two years thinking he loved me but now i know he never did and it hurts because i did everything i could to make him happy and nothing was ever enough. It makes me feel worthless. I don’t know what i did or why he’s doing this or what any of it means. We purposefully had this baby together and he told me a few months back he wished he was aborted. I don’t see how you get someone pregnant on purpose then wish that, or leave them just because..

I already have sole custody, he gets my son two days a month. He’s also been saying I’m keeping him from my son and being petty just because I’m following the court order that he willingly signed and threatening to take me to court to go through the process again when the agreement was signed in November. I also haven’t seen one child support payment and he’s 1,800$ behind. I told the child support office but haven’t heard back .