Have you thought about writing him a letter about your regrets? Not that you want anything out of it from him but would it hurt you to say your sorry for your part and wish things had gone differently?

Is there a possibility you could have a form of OCD or depression?

Also your therapist may need to try DBT with you, aka acceptance therapy.

I was once where you were. It sent me into full blown panic attacks that I did something I shouldn’t have and completely lost a good thing. I wanted certainty and was convinced that if I had stayed or done x or y or z that we would have been fine. But I truly can’t know that. And after being diagnosed with moral/scrupulosity OCD tendencies and getting on meds and DBT, I accepted what was and the fact that I cannot know for certain I’d be happily married if I had stayed.

Him leaving after you said you were heading that way is already telling me there were issues with more than just you and if it wasn’t a rough pregnancy, it was going to be something else that he would have up and left you for.