I F/32 had to get po on M/32 boyfriend. Help?!

I F/32 had to get a retraining order on M/32 boyfriend who I’ve been dating for a year and half. who’s also a cop.His drinking had gotten really bad the last 6 months and has caused lots of issues and I usually end up leaving the house for a day or so. Last Tuesday night I got home and he was already drinking and I tried to talk to him about a concern I was having for my oldest son. It ended up causing an argument between us. We have a three month old son together and he was caught in the cross fire because his dad was holding him. Anyways this argument started outside and we came inside and he took the baby to the bedroom and I stayed in the kitchen for a minute. When I went back to the bedroom I seen the baby laying face down on the bed and I asked what he was doing and his dad stood him up and said watch this he likes it and let him fall on the bed on his face. I told him he doesn’t know he likes it he’s just a baby and that could hurt him. And he just said no he’s fine. Then I went to the bathroom to get the babies bath ready. I walked out to get a towel and rag out of the babies room and when I got back to the bathroom. My son’s dad was already giving him a bath. I tried to take over but he wouldn’t let me. I told him to use a specific soap due to the baby having a bit of cradle cap. I can’t exactly remember why but his dad and I got into another argument having to due with the soap. As he was finishing the babies bath he turned him over to spray him off with the shower head then picked him up by his arm to spray him off. Mind you the baby wasn’t even three months old at the time. I immediately lost it and told him that he was gonna hurt him and that could pull the babies arm out of place and he turned around and yelled at me that he knew what he was doing because he has more experience and children then I do all while the baby is crying. I was so mad and walked to the bedroom and got the babies stuff ready to dry him off and look at his arm. He’s dad wouldn’t give me the baby and kept walking away from me while I was trying to get the baby because he was still crying. I finally talked him into giving me the baby and he pushes the baby towards me and say here take him. I get the baby to the bedroom and start breastfeeding him to get him to calm down. After he’s calmed down a bit I grab some of our things and leave. I was afraid something else would happen. As I’m getting the baby in the car his dad is outside and yells at me that I’m taking his kid away again. I get the baby buckled in and get in my car and call my mom crying because I can’t believe all that actually just happened. She tells me I need to call it in and probably go have the babies arm looked at since he’s still upset in the backseat. I do just that! The first officer that came told me it was a civil case and looked at the baby a second and left. I took the baby to the er to get looked at to be safe by the time I got there the baby had fallen asleep. I go in see the doctor let them know what happened and the ex ray him because I wasn’t 100% sure which arm he picked him up by because I was so mad in the moment he was holding him up like that. They keep us there a couple hours till they get the x rays back and thank god his arm is fine. They wrote up a report and were legally required to contact DHS on it. Another officer shows up when I get back to my mom’s house to take a report and advise me to get a protective order for the baby for the time being. The next day I do just that and DHS shows up at my mom’s to talk to me. I don’t like DHS whatsoever and hate ever having to deal with them because from what I’ve seen they don’t do any good for the people actually doing the right thing. Anyways I talk to two different DHS workers and even an investigator over this crap. And there’s a temporary protective order in place. But right now all the adrenaline has worn off and I’m hurt, heartbroken, overwhelmed and completely devastated over all this. We had court this Monday and I was told to get a lawyer because he has one and it was rescheduled for next Monday. I have no money to get a lawyer so I’ve contacted someone to try to get an advocate instead. So I’m being torn on what is the best thing to do. I know he loves his son and I wouldn’t think he’d have ever done this on purpose. The man’s literally a cop so he’s dealt with things like this. I want to believe he was just drunk and not aware of what he was actually doing but at the same time I’m my child’s mother and I have to protect him no matter what. I love the man and we were building a life together and then this happens! Im just really confused on what I should do. Would this ever work itself out and he change and learn from this so my son can have his parents together? please help!!!