Divorce may be imminent and I’m a wreck

I have posted a few times in here before, specifically about task sharing and other marriage advice. But tonight I think I’ve decided I’m done. My spouse and I have a child who is three. He saw us have a blow out fight on Sunday and now any time I seem a bit sad or tired he asks me “daddy mad?” I cannot do this to my child. When hubby came home from work tonight I told him what our child has been saying and instead of suggesting we find a better way to communicate, he told me it was “my fault”. This is so narcissistic and unlike him it’s not even funny. But I don’t know where to start to rebuild my life….whats the first step?