Help me walk away!!

Im 23 i have two kids under 3 and currently 7 weeks pregnant. I’ve been with my husband for 7 years and married for 3. I knew since way before we got married he wasn’t ok mentally and neither is his family. I literally had a physiologist tell me they are a disfuncional family but I was young and dumb and thought he would change for the better and boy was I wrong!! My oldest child has seen him verbally abuse of me since he was in the womb. Now that he’s a little older and so so smart he asked me if daddy was getting after me because he was screaming at me before he walked out and slammed the door to our RV so hard that it literally shook it! My heart broke into a million pieces. I’m ready to leave this toxic alcoholic person I’m just so scared of what life will be like without him after 7 years together and now 3 children. I’m scared my babies won’t understand why I had to walk away. Call me crazy but I’m scared to see him with other people. I’m scared to never find someone who wants to be with me and my 3 children. I’m scared of all the posibilites if I leave him. I no longer cry over him when this happens. He screamed at me for tell him to go to bed because he works tomorrow and he was drinking more alcohol than he had bought for today I told him to calm down because the kids were listening I told him to calm down because I was scared and my baby wasn’t visible in the last ultrasound and I’ve had an ectopic pregnancy before. He told me off up and down and left. I have more than enough support to leave him but I’m still so scared. Help me please