Need advice for minor who is being emotionally and mentally abused by xhusbands girlfriend. They have been blocked, threatened, yelled at

Your question cannot be answered in this forum, as more information is required.  For example, 1) who is the custodial parent? 2) why is the ex-husband allowing his girlfriend to abuse the child? 3) How did the mother become aware of these allegations? 4) How old is the child?)  5) What if anything has the mother done to address these concerns? 6) How often does the child see the father? 7) Is there a valid court order in place? 8) If so, when was the order entered? 9) Was the order by agreement or did the court order the current arrangement?  This is only a few of the many questions that need to be addressed before moving forward.  I suggest that you arrange to meet with a lawyer family lawyer in your area to discuss this matter in greater details.  Most lawyers charge by the hour.  Therefore, make sure you ask the lawyer his or her hourly rate to avoid any misunderstandings about payment. Best of luck~