How can we both leave together?

If there are no court orders to the contrary, you have full custody of your child by default and can leave with the child if you want to. If you think he'll try to stop you, call the police and ask them for assistance.

The very best thing for you to do is to have a full discussion with a local family lawyer. If you were not married to the boyfriend, you make all the decisions regarding the child, and already have sole parental responsibility unless and until the boyfriend gets to court and has his rights established with a paternity case.

First, unless there is a court order establishing your boyfriend's paternity of the child and/or establishing timesharing, your boyfriend has no legal rights with respect to the child, yet. You could go to your mom's in the same county with the child. Second, you would be well-advised to file a paternity action to establish your boyfriend as the legal father of the child, establish parental responsibility, establish child support, and establish timesharing, among other things. Consult with an attorney to discuss the specifics of your situation and your options.