My Child's Paternal Grandma

I'm in need of some serious advice I need you to have an open mind about what I'm about to say. But I also need pointers. Back around legit Feb 26th, my child's dad and I got into a very heated arguement with his biological mom and sister. She called the cops and got him arrested. Threatened me, and everything. They even popped up at my job and would drive past my house and stop in front. At the time I didn't know I was pregnant but I was. His mom and sister steady threatened me for about a week or two. I then found out his mom stole my identity. Filed my taxes, put a phone and cable in my name. So since then I haven't spoken to his biological mom or sister. I absolutely love his step mom though. When I finally found out I was pregnant I always said my child wouldn't be allowed around his biological mom. About a month ago his mom and another female pretty much bashed me on social media. He agreed up until recently his mom and him made up, I'm not upset at that because that is his mom. But now he's talking about going against my wishes and taking my child around her and I need to forgive and forget. But I honestly don't feel safe or comfortable around her. Because of this I want to know if I'm wrong for feeling like I do? & if there is ANYTHIG I can do to make sure she cannot be around my child? I need pointers, tips, and honest advice.