My Ex-Boyfriend wants sole custody of my son

Hello there Everyone!

I live in Indiana and I am in need of more advice. My ex-boyfriend and I have a 3 year old son together. My ex is not on the birth certificate though my son does bear his last name, which I am going to change back to mine. My ex has no involvement with my son except occasionally giving me money and sending me personal threats via text. He claims I do not allow him to see his son despite me going above and beyond to make him aware of my schedule and inviting him to birthday parties, fairs, beach days etc. I have spoken to a lawyer previously and she said that regardless of my son's last name since a VAP has not been filed and a paternity test has not been performed, I am legal sole custodian and my ex will have to take me to court to get even the slightest visitation rights. Is this correct? Usually every month when I ask my ex for financial assistance he goes on his "I am taking you to court" rampage for visitation. So, my second question is, should I get a lawyer now before he starts any sort of paternity establishing process? Can I get him to submit to a random drug test? Can I request a home inspection for his apartment? What do? Thanks in advance guys. I don't know who to turn to and honestly I am terrified of him being alone with my son. He was abusive and I regret not reporting it.