I know when I was at my worst, I used to say some really hurtful things to my hubby and told him constantly to find someone else because I am worthless as a person and that he can have the kids.
Once useful bit of information that my Drs said to my husband is to keep reminding myself that it is not me that is saying the horrible things, it is the illness making me feel the way I am.
For a partner who has never suffered depression (yet as they say everyone will at some point in their lives), it is hard for them to understand the darkness the world is. Before having bubs we also wanted to celebrate all the fantastic parts of becoming a family, just like our partners and we too have been cheated from that experience.
However, I know from my own experiences those moments do come so please hold on and keep reminding yourself that its the illness.