I know many judges actually follow the law that most of us have stating that refusing to allow a child to develop a parental bond with it's biological parents is emotionally abusive to said child. Abusive parents usually don't get custody. OP, I would really look at ways you are going to allow your boyfriend to be a father, if he is one, rather than cut him out. It will not look favourable on you.
Just imagine if someone was threatening to stop you parenting your unborn baby because you being known as the legal parent would inconvenience their life? Wouldn't you act a bit crazy?