Need advice!

So basically the father of my baby hasn't been in the picture for the last three months, he left when I was about 9 weeks pregnant but now all of a sudden he has be threatening me and telling others that he will be taking the baby away from me (when he's born) and will be filling for full custody.he is not a stable person he drinks and does drugs on the regular. He's never been supportive of this baby nor has his family they actually tried to force and abortion apon me. I'm terrified about what will happen and don't know what to do if I should/could file for full custody or wait it out. Someone please help out here