Physically abusive bf...

So my boyfriend and I have been together for over a while and have a 3 month old daughter. When we first started seeing each other we would drink and hang out, after a while, when he would drink he would talk down to me and make me feel literally worthless. Now, he drinks and still belittles me and hurts me. Only some nights he acts like normal and lovey dovey. Idk what to do.. it’s only when he’s been drinking that sometimes he behaves this way and hurts me. Last night while I was holding our daughter he used my hair brush and hit me repeatedly on the shoulder until I was sobbing out of breath and then mimicked my crying and tried humiliating me.. then after I was done crying had the nerve to ask me why I was sad.. idk what to do. I love him so much and he’s so perfect when he’s sober but when he’s drunk is when he turns into the devil