What can I do to protect my child from him?

If you're not married, you don't have to. However, if the child ever receives any assistance from the state (medical, welfare etc) the state will bring a parentage action to get child support. The father can also bring a parentage action if he wants to make himself a legal father. Otherwise, don't have any contact with him because if you do it makes it more likely he will want contact.

Wait until the baby is born and don't put his name on the birth certificate. However, if he wants to be part of her life, he can file a paternity action and if it establishes that he is the father, he will have the right to custody and make decisions on her behalf along with you. He will probably also have the privilege of paying child support. This assumes that he is "normal" and not a drug abuser, inclined to violence or a pedophile. He has as much right to the child as you do and if he wants to be, will be in your life for at least the next 18 years.