Struggling with no contact

It isn't easy going no contact. Especially when they're kids involved and you're used to having that person in your life and by your side. I hate playing the victim or reaching a point where I feel sorry for myself, but I've been subjected to so much abuse that I'm honestly used to it. My ex and I are still broken up, and I have attempted to go no contact numerous times throughout our breakup. It isn't easy though because I'm currently 8 months pregnant and he uses that and the kids as an excuse to contact me. Once were on the phone he knows exactly what to say to manipulate me and get me exactly where he wants me. So it's become a sick cycle. He does something to hurt me, I tell him to leave me alone, and he does for a few days. Then he comes back like nothing happened or he acts like he's truly sorry and wants to be a good father and be a family. Once I start to believe that he's changing he switches up and ends up doing the same exact thing again. Last week het threatened me and told me that it he ever found out that I was dating someone else he would take his kids far away and think about telling me where they were. He also told me that he didn't want me with anyone. Then a few days following that conversation he told me that he never said that and what he said was that he didn't care if I dated someone he just didn't want the new guy around his kids. His wants and ideas constantly change from day to day. It's almost as if he's a different person every single day. Then he went from calling me all day and telling me all he wanted was his family to being completely distant towards me and telling me that he only wants to speak to me regarding the kids. He also said that he still wanted to come live with us but he wouldn't speak to me while living in my house and that he would completely ignore me unless he absolutely had to speak to me. I asked him what was the point in living with me he told me because he needed to be there for his kids. Last night we had a disagreement because I didn't listen and do what he told me to do. This morning he woke me up by calling my phone nonstop. When I finally answered he yelled at me and told me that he hated me and that he regretted ever having kids with me. That I was a sorry excuse for a woman and that he hoped I would have a miscarriage and bleed to death while giving birth. When I started to cry he told me that I was weak and all I did was cry like a child. I tried to hang up so he would leave me alone but he refused to stop calling. Two hours later he called and told me that I should blame myself for how he treated me because if I had only listened and followed directions he would have never felt disrespected and he wouldn't have felt the need to disrespect me. Then later in the day I say that he was adding numerous women that are in one of his pharmacy tech classes and attempting to speak to them and compliment them. The same person that threatened me and told me that I shouldn't talk to anyone especially because I was pregnant was attempting to talk to other women even worst while he was living in my house. I felt so disrespected because he's trying to live with me, telling me he wants his family meanwhile he's at school trying to talk to different girls. When I confronted him about this he told me that I was crazy and that he wasn't doing anything. Then tried to turn things around and patronize me and tell me that he loves me just not like that but he still has feelings for me which is why he doesn't want me with anyone else. That we need to put things to the side and be a family regardless of what he's doing. So basically he wants us to be a family and live together while he's living his life and doing what he wants? I just don't understand why he thinks it's okay to treat me this way especially while I'm carrying his baby and taking care of his kids on my own. So I told him that I didn't want him living with me anymore and that he could see the kids but I didn't want him contacting me for anything else. He refused to listen and threatened to break into my house if I wouldn't let him in. Then he tried to switch things around and told me that all he wanted was to see his kids when I told him he could. I'm stuck I don't know what to do...