Literally can’t let him go need help

I am in such an abusive relationship......

My boyfriend treats me like shit. Don’t get me wrong sometimes he’s great but others I don’t know who he is it’s like his eyes go black and his soul leaves.... he’s never hit me but he is just so ridiculously mean sometimes. Today he called me stupid, and a bitch in front of his whole family

And then tried telling me he didn’t want to be with me when he got home

All so I told him we need to make this work

He’s still being so vulgar with me. Why can’t I let him go..... why can’t I just say I’m done and let him leave...

I am 6 months pregnant... but I do love him so much and I’m so scared to lose him..... but I know I don’t deserve what I get put through with him....