Soon to be father. Need to know what steps I must take in order to secure custody of my child once he is born

More information is needed for the experts to help you properly. What is your definition of "crazy?"

Is this a new development? Because you're the one who chose to sleep with this woman and I assume your old enough to know what happens from that act. And the courts will see you willingly participated. So unless she can be legally committed then you may only get standard custody.

You will need to hire an attorney and make a motion in court for custody, you will have to prove of course that the mother is unfit with evidence that the court will accept