Custody

What are the chances of my ex getting custody of my son? We live in different states, unmarried, he hasn’t seen him since he was born. He’s threatened not only me, but my family as well(have screenshots). He told me he was going to get custody to screw me over. It breaks my heart imagining him being able to take my son, he gets so scared of people he doesn’t know and screams and tries to get away from them. My ex doesn’t know anything about how to take care of my baby and I’m so worried. I’m 19 and he’s almost 20.