There are many instances where a parent is addicted to either prescription drugs, or to illegal drugs such as cocaine or marijuana. When this occurs and there is a custody dispute between parents, it is most important on the very first visit before a judge in the custody litigation to request drug and alcohol testing, as well as demanding that if the court sees fit to permit limited visitation, that it be exercised under careful supervision. Without alerting the court to such requests at the outset, you may be held to have waived such rights to do so.
With regard to supervision, you may consider a member of the spouses family to do so if they are responsible grandparents, or there are other options for supervision run under the courts auspices. In any event until the parent admits his addiction and takes steps to enter into treatment, which could include anger management if this behavior is also exhibited, supervised visitation should remain in place.