Can I get sole custody of my baby?

We have a 2 week old baby. We have been married 5 years and in the last year my husband has been mean (meaner than normal) and violent. He breaks our belongings and says he does it so he doesn't hit me. I called the police and they weren't much help (this was 7 months ago). I tried my best to hold this family together but I cannot take it anymore and I'm worried he'll hurt me or the baby. He has mental problems and has seen a shrink for bipolar disorder but isn't on medication for it. I don't want him to be alone with our child and he actually scares me at times. If I have to go to court - could I get sole custody? I would die if I thought my baby had to stay with him alone without me. He wouldn't have a clue what to do and that terrifies me!!!!