I need advice please

Please I need advice. I know what the common sense answer is however it can be complex. I have an 8 month old son. My son, boyfriend and I been living with his mom. My boyfriend is my sons dad. Now I’m thinking ex boyfriend but sometimes my head is screwed up, like today got screwed up. To make a long story short, me and my boyfriend were exchanging words, nothing too bad just going at it for a min. Mind you I’m 33 he’s 27. His mom was standing there, she got up in my face, called me bipolar and all this crap, never been diagnosed with it, whatever. Next thing you know she smacked me in the face. Well I had dialed 911 because they weren’t going to let me leave. In the background you can hear arguing and my sons father saying you can’t hit people mom, this and that. Well the police arrived, she took off bc my partner told her to leave. The cops got there and my boyfriend lied saying he didn’t see anything. Said he didn’t see anything. Gaslighting me with police when I know he was there you can hear him on the call. Anyways he’s like begging me to come back. Everyone I know is advising me to stay away. So I am. I’m not going back. Not with my son. Luckily my son was with my mom for the night and we are back together. It feels good to be with my baby. His mom has been abusing me for months this is the first she got physical. Back in October she went crazy and tried assaulting me with my 4 month old in my arms. Someone please help me. This man has stabbed me in the back and basically I’m done. Idk what kind of advice I’m looking for. I guess maybe reassuring me that everything will be ok. Maybe tell me he’s a pos for not having my back and making his mom accountable for the things she has done. It’s just been too much. Not only am I living in their house, following the rules doing what I can. I told my partner I don’t feel comfortable being alone with him and the baby. This is the final straw. I can go on for hours but the abuse ends. The abuse ends today