My heart is BROKEN.

I had a stillborn child in May of 2017. I had 1 period since, and found out I'm 6 weeks pregnant a few days ago. My SO was so excited for our son's arrival, then he was stillborn. Now he is telling me if I don't abort this child he's not going to be with me and he's going to go do whatever he wants to do and I can go figure out what I want to do. It hurts me because how can you go from happy to not wanting anything. I feel like I have to choose between him and this rainbow baby and it's so hard for me. I'm 19 but we've been together 6 years good jobs, own apartment, 2 cars, etc. We still have all of our baby stuff in the spare room and I just don't know what to do I'm so scatter brained and hurt and he doesn't seem to care whatsoever..... What do I do?