I am sorry you are going through this. As long as he is considered dangerous to himself or others probably not, but if he is on medication and can prove to the court that he can be careful he may recieve visitation under conditions. You may want to retain an attorney to begin assembling your evidence against him if you don't want him to have any contact. I wish you all the best and I hope that things work out, take care.
Legal disclaimer: The response given is not intended to create, nor does it create an ongoing duty to respond to questions. The response does not form an attorney-client relationship, nor is it intended to be anything other than the educated opinion of the author. It should not be relied upon as legal advice. The response given is based upon the limited facts provided by the person asking the question. To the extent additional or different facts exist, the response might possibly change. Attorney is licensed to practice law only in the State of Massachusetts. Responses are based solely on Massachusetts law unless stated otherwise.
You should act immediately if you feel your children are in danger. You can petition the court to eliminate or restrict his visitation. many counties have sites for professionally supervised visitation. The court will most likely appoint a Guardian Ad litem or an attorney for the children who will listen to your concerns, conduct a thorough investigation and make a recommendation to the court.
All issues regarding custody and visitation are determined by what is in the best interests of the child.
Based on the few facts you have provided, I would imagine that you, as the parent that has been with the child since birth, would be the logical parent to have custody.