feeling depressed most of the time

I am pregnant with my first baby with my partner of 2+ years. I'm close to the end of my first trim and he's still not taking responsibility for us. Not even accompanying me to tell my parents about it. My father still doesn't know. 
My bf has been cheating on me in the past and that still haunts us. I feel he's still cheating on me that's why he's not manning up for me and our child. This is supposed to be a happy time for me, a baby is a blessing. But I can't help feeling sad most of the time because he doesn't give a damn about us. I have told his family about the pregnancy and they don't care at all. I'm confused about what to do. This is supposed to be a shared journey of love and joy with the coming of our child, but I'm treading on my own. It's hard to be alone in all this.