Abusive? Need advice

Hi friends it’s hard for me to post this because it breaks my heart. I feel like I’m betraying the father of my child. But I need to vent and I need advice I need to know I’m not the one with the problem. Well my SO drinks everyday! To the point of where he had a couple seizures while he was trying to stop. He gets abusive and has hit me before has called me names for the past 3 years. Mind you it wasn’t like that in the beginning.. well the names are just destroying me. I get called fat fuck, piece of shyt, bitch, every nasty name you can think off he says it. Well we had a baby by surprise. He already has another child from a previous marriage. And well my son was a shock and a blessing. I ended up sick and almost dying after having him and my SO and his child had to help watch him while I was in the hospital for 2 months. I keep getting blamed and put down by him because he said he had to watch my son because I could not. He constantly reminds me of how I couldn’t-breast feed my child even though It was all I wanted that bond with him while I make sure his tummy is full and well idk I was so sure I wanted to breastfeed. He constantly brings it up how I couldn’t breastfeed and how his ex was able to feed his child. Calls me worthless. Eat.. well to be honest I see the problems but I’m just so afraid to leave. I was so independent and I feel like he just broke me. I’m scared and idk why I know I can care for my son! It will be hard but not impossible and I sure won’t be the only one. The hardest part of this is not him calling me names is that he makes our son less in front of his child. He tells everyone, friends and family how bad my son is when I’m around and how says things like he’s so fuming lazy he’s not even walking completely yet. His child has hit my son trying to discipline him and when I say something like please don’t hit him I’ll make sure he is doing the right thing eat I’m his mom kind of thing. My SO tells me to shut the fuck up and proceeds to fight or hit me in front of both kids. Idk what to do. I just need to get it off my chest. I’m so embarrassed to tell my friends or family. I’m scared. Sorry it’s so long!

UDATE- I am seriously crying because I feel like a coward a failure for my son. I didn’t know that an I love you from some one I never even met and just read my story would make me feel actually loved!! Crazy loved by a stranger and it made me feel like I’m ready to leave this mess behind me. For those of you who asked about the child’s mother. She is living her best life with mental problems herself. She never stopped bothering us or even accepted our relationship. We caught hard to get his child 50/50. And that’s one of the reasons I stayed also for him. But, my son comes first!! My boy! I would do anything for him and I need to get my it together for him. I feel good friends! Just about 30 min ago my SO was calling me names because I asked him to stop drinking and take care of himself since he’s been getting bloody noses. He just said to shut the fuck up and look at my fat ass in the mirror. I told him I was leaving him and he said good take your son with you. I already have mine and you guys can go fuck yourselves. I laughed and said you think I’m joking don’t you? He replied with a simple I’ll sign the divorce papers and sign your son over you can live through him. I said okay. And it’s not living through him I need to leave FoR HIM. He laughed and went to the living room to drink. He doesn’t know I have this phone either. I feel so good right now. I’m still scared because as the night continues.. he’ll keep drinking and it’s at night where he’ll be drunk and start attacking me. I have proof of bruises and even some from 2 days ago. Two bruises on my chins so hard I have hard bumps protruding. I deserve better and my son does too!