Visitation/restraining order

My husband’s ex would never agree to sign a separation agreement. That is the only document that outlined his vistation rights. The girls are with us every other weekend and a night during the week while the mom is on-call. My husband is Bipolar and several doctors over the past few years have told him that he needs to have minimal (if ANY) contact with the ex. She berates him to the point that he has had to be hospitalized for his own safety. She knows exactly what buttons it takes to push him to the breaking point. ??? What do we need to do to get the vistation “official” so that we can then get a restraining order to prevent her from making direct contact with him? He lives to spend time with his children so it is VERY important to his mental health and well-being to ensure that she can not with hold visitation. Would the agreement be the appropriate place to specify how the arrangements for visitation are to be handled (ie third party) ?