How do you deal with a breakup during pregnancy?

Im at the point where I feel so depressed when it comes to my relationship. The constant fighting and he is just not trying. When is enough, enough? I feel really town between trying to make a relationship last or moving back to my parents to work on happiness by myself...
Im in therapy with my SO, but he does not try. He is short tempered and just not patient with me nor is he considerate. I'm just starting to understand that this is not the life he is ready for... this relationship doesn't look fixable. 
I have to do what's best for my baby and myself...