My Ex is Threatining to Come and Take My Son

My question involves a child custody case from the State of: Arizona

I am in need of help!! My ex and I went through a very nasty divorce a few years back. There were issues of substance abuse on both parts. Through the proceedings i lost custody of my son to him. When the divorce was finsal, we immediatly got bach together (stupid me), anyways we did great for about 2 years. During that time we went into my lawyers office and he signed a document stating that he agreed to joint custody and we were living together and working things out. I currently cannot find a copy of that ANYWHERE, at home or via internet. I since then fired that lawyer because he was representing me in a probate case and I wasn't happy with the representation in that case or in the divorce case. A year ago my ex moved out and since then visitation has been with me full time except every other weekend with dad. He now is threatening me and wanting to come and take my son and have him 1/2 the month, so in his words he doesn't pay support. It is to the point that he is harrasing me. What do I do?