Do all emotionally abusive relationship end up being physical as well?

I’m in an emotionally abusive relationship. There’s moments where he can be so nice but a lot of the time we are arguing. He’s always calling me names and saying I’m crazy and something wrong with me. And the thing is SOMETIMES he makes me believe that it really is me and I am crazy. Last night for example he said I’m a sociopathic bitch that ruined his whole life. And not even a minute later he’s telling me to just love him and be there for him. Every 1-2 weeks though our fights get so bad. The look in his eye is scary. The way he looks at me and yells at me is scary. Our relationship went downhill as soon as I got pregnant. And it got worse the day my son was born. I don’t get why I don’t just leave. My son is not 6 months. Has anyone been through this.m? Can anyone give me advice?