My whole world just ended

I just found out my husband of 8 years have had three entire relationships while with me. He has lied to those women about me. Telling them I am nothing and that we don’t live together. He has told these women bad things about me. But got upset because I reached out to the girl he was cheating on me to get the truth. He’s mad at me. I’m currently pregnant with our third and I just don’t know what to do. He was the only person I had in this world. Whole time, he doesn’t even want to be around me. I don’t know what I did wrong. Can’t sleep. Can’t eat. Can’t think clearly. Even my three year old noticed my personality change. How do I get out of this mindset. What do I even do? I’ve only been with him since high school. How can someone do this? Why would anyone do this.