How to keep this maniac away from my son?

I just left my bipolar, alcoholic MANIAC fiance. I am 7 months pregnant, and one day he decided to drink all week and totally flipped. Prior he had been so loving and excited and we had never been happier. Then he TOTALLY changed. He accused me of trying to kill him, killing my baby, stealing his money, having sex with neighbors in our bed, every possible thing you can imagine. All this from a very loving affectionate man who promised to stay by my side. His paranoia is off the charts. When I left, he hadn't eaten or slept for days and was drinking like a fish every night, but we parted on semi-good terms. I came back to the house after a week or so of little to no contact (the contact we did have he made it clear I wasn't welcome in my own home to stay away. Keep in mind, I'm pregnant with this man's child)! and the police made him leave so I could stay there. I went in the house and it was trashed, holes in the wall, writing on the wall in baby room, condoms everywhere and the handwriting of a woman on the calendar marking days 'Lexi came for a visit'. I was devastated he would do this in and to our home, I threw up maybe six times. :( I can't describe the pain. I have now left the state and won't be going back. How do I ensure this guy NEVER gets around my baby! He terrifies me! He has a shady record (DUIs, mental hospitalizations, and owes the IRS money for cheating on his taxes)