Having a hard time😪

I left my sons dad about a month ago. I just wasn’t happy, there’s too many major relationship issues that can’t be worked out without help. Basically our issues are other girls, won’t ever communicate with me, if I do ever tell him what’s bother me he doesn’t do anything to change it or he will for a week then go back to treating me the same, choosing drinking with his friends over spending any time with me(we don’t have any days off together). Just doesn’t make me a priority in his life. Yes I’ve talked to him about everything and he just doesn’t care. Well he suggested we go to therapy because he doesn’t want to break up. But last minute after I got everything set up, he said he didn’t want to go. That he doesn’t see how it would help. And he doesn’t want to work things out anymore. I know it was best we are not together, but I hoped we could at least try. I’m taking it a lot harder than I thought. And I’m having a really hard time with our son and having split days. I’m getting use to that. But now he’s talking about going to see a lawyer together to get everything on paper on how we have our days with him. And I agree, but it just hurts to have to even do this. Also my mom said the other night while I was at the gym my son woke up screaming saying “dad” and it was clear that’s what he said. He’s only 22 months old. So that just broke my heart😔 I grew up with divorced parents who were apart when I was also 2. I never wanted this for my child. I feel as I failed my son. I do wish his dad would work on things with me because I do love him, and I know we could be great together if he’d just grow up and realizes what he has. But I know I can’t change him. I just don’t know what to do. I feel so broken💔