What legal resource do I have regarding my 3 yr old son in a child custody or visitation case?

My son's mother has not gotten over our break-up(we were never married) She has routinely harred me, my family and friends by calling and leaving obscene messages(especially females).She has broken into my email account as well as solicited my cell phone calls through a internet broker to do this. I have physical proof of all this. My main concern here is that her obsession with me is putting our son and her 10 yr old son in danger because she has no respect for my or anyone else's privacy. She verbally abuses people that do not know her and some want to do her harm because of the nature of her obscene behaviour that borders on psychotic. I know that she suffers from depression and bi-polar disease and I try my best to let her know that she cannot act the way she does. I see my son because she allows that on a regular basis as I am heavily involved in his lfe but she is physically and verbally abusive to me in front of him. I believe an outside party is needed to prevent a trajedy.