What do I do?

I don't know what to do anymore... My fiancé and I are fighting like crazy... I've been told my entire pregnancy that my baby isn't going to make it or there is something wrong with my baby, no one I know has ever gone through trisomy 13 in a pregnancy, I feel so alone. I feel like I don't deserve to be happy in my relationship and I don't deserve to be a mom, I feel like I don't deserve anything good for that matter, I feel like a complete mess up. I feel like people's lives would be better without me in them. I'm terrified..