I am so sorry that you feel as you do.  You need to understand that if you do not comply with the visitation order then it will be your Mother that will be held accountable by the court.  The short answer to your question is 18.  The long and involved answer is that your Mother must go to court and ask that the visitation agreement be modified.  You will be asked to testify.  Your reasons have to be valid and not he is too strict.  Think about it.  Good luck.