What are my chances of getting full custody if the father has been in prison for eight years?

I am going to be filling for full sole custody of my 7 year old son, his father has been in prison for 8 years. He will be getting released next year in February. He thinks that just because he is getting released he will run what I do with my son & pick him up whenever he feels like it, he told me that if I move out my house that my son can't go live with me and for his mom to raise my son? So I am going to file for full sole custody & divorce what are the chances ? I do not mind him visiting I'm not trying to take that away from him but I rather be on the safe side & mind you his charges are very violent crimes. What are my chances?