When is enough?

I feel so lost. I love my boyfriend. He’s an amazing guy and we connect so well. Laugh and joke and have the same goals and all. But when he drinks he is a different person. My son is 5 months old and my bf about a halfway through my pregnancy started to drink a lot. He would drink about a bottle of rum every other night and the nights he didn’t have that he would drink a 6 pack of beer or a whole thing of wine. When he drinks he gets mean. He never physically done anything just verbally. He will put me down and make me feel useless and make everything my fault. He will threaten to leave and will refuse to say he loves me. He just makes me feel like scum. The next day he is always filled with sorrow and regret and tells me it won’t happen again and that he gonna work on himself. This all stopped when my son was like 3 months old cause I had enough and he made the effort to stop drinking. He went from then til this last week without any drinks. Now all sudden he’s back to drinking every other night and is back to the same old pattern of putting me down, making me cry and then him going to sleep. I feel broken cause I love him and I want it to work. I also don’t want to give my son a split home because I had that growing up and hated it. My son such a smiling and happy boy and literally smiles at everyone. He loves his daddy so much and gets beyond excited when he’s home. I wouldn’t want to take this life of 1 home family away from him and take him seeing his dad daily away. But at the same time my heart hurts. I feel broken and numb. I feel like when he drinks I need to take my son and leave apartment. I feel like I’ve failed my son. I just wanted a happy family where I could give my son everything I wanted but here I am crying and feeling like I’ve failed my son so much.