Leaving an abusive relationship

My boyfriend has never been abusive to me the five years that we’ve been together. All that changed the other night when he got drunk and got mad at me. He choked me so hard and threw me on the floor and then held me in one of our kitchen seats. I have bruises, a big red mark on my neck that looks like a hickey, my wrist hurts really bad, and well my whole body just hurts. I know I need to leave him but I just can’t get myself to do it because we have a nine-month-old daughter and I don’t know how I’m going to do it alone and frankly I’m afraid to be alone after being with somebody for this long. I really need some wise words and encouragement. I have also been dealing with postpartum depression the past few months pretty severely so I just need help. I am asking you all as sisters to help me with positivity and encouragement. Maybe even advice