The father of my newborn is trying to gain custody and I'm afraid they will grant it to him?

I got a protection order against the father while I was pregnant around 5 months. As soon as I had the baby, he had someone call the hospital and ask if I was going to let him see the baby. I hung up and now I got a summons from dcse for paternity test coming up soon. I don't have a lawyer but I'm working on either having my grandma pay for one or get one pro bono if possible. He was extremely verbally abusive and physically abusive. He's an alcoholic and recently got charges for public intoxication and assault before that. He was on probation from the assault when he got the public intoxication. He's reckless and he gets in fights all the time with his gfs and with guys. He had me hooked on painkillers before I was pregnant then I got on Suboxone and doctor told me subutex was safe to take during pregnancy.. I'm worried he will use that against me in court although he doesn't have proof that I know of except he can get the ppl around him to testify. I also have a video of my 6 year old child saying he gave him beer because he gave it to him right before my mom took the lens cap off. When it happened I thought my son was joking because I didn't see it happen then he said Shh don't tell on me after my son kept repeating it. I'm so afraid they are going to give him rights to the baby and my baby will be exposed to a really bad environment and won't be taken care of properly. He's mentally ill and doesn't care about the well being of the baby he just wants the baby because he likes babies. He likes to make up and twist around stories to get what he wants and make himself look better. How can I keep him from getting rights??