I had doubts too about the relationship because it was long distance (a 9-hr flight) but at least I was willing to give it a shot. Working through differences, compromise, and accepting that everyone is different is what I think builds an emotional bond / relationship that lasts. I suppose at the end of the day, he just didn't love me enough. His gut feeling was more important than me.
I'm so sorry this happened to you. I can feel your pain reading your posts. It's hard to deal when the other person who stole your heart told you you stole her/his heart and then one day, poof, they're gone, hanging you out to dry instead of working things out together. Please take care of yourself. You want to be strong enough to be there for your baby down the road. My thoughts are with you.