Visitation issue-ATTORNEYS PLS GIVE SOME DIRECTION

My ex was supposed to have visitation this weekend. (he only has every other weekend visitation) In our agreement that was done in 2008 states that neither of us are supposed to have visitors of the opposite or same sex outside of blood or marriage when we have time with our son. Ex got married in 2008 fine. The end of march 2012 his wife left him. In May I was made aware by my son who is 5 yr old that my ex had a woman stay overnight while my son was there. I confronted my ex about it who denied and said it was his neighbor.
This monday, I was informed by my ex that this woman was coming from out of state where she lives with her children to spend the weekend which is his weekend. He is stating that he has decided to marry this woman and this will be an ongoing thing as she is moving in the next 6 mos. (he is just seperated from his other wife and the year won’t be up for divorce until April 2013). He demanded that so he can uphold the agreement that he pick up my son sat morning drop him off sat evening then pick him up sun morning and drop him off again sun night. I refuse. I gave the suggestion of having this woman stay in a hotel and him and my son stay at the house. he refuses. he states that he is forfeiting the weekend bc I will not give in to his demands and I am committing neglect. On tuesday, I confirmed that he was still unwilling to follow the agreement by having them stay at his house. again he states the he is forfeiting his weekend bc I am refusing his demands. I advised him that I changed my plans to accomadate having my son. (he has a history of changing things alot)
This afternoon (wed) he emails stating that they are now going to the beach and will have seperate hotel rooms. I refuse stating that I gave him the opportunity on two different days and he confirmed that he would not take my son and abide by the agreement. I do not see having different hotels rooms any different that trying to circumvent the agreement. How is it really different than claiming they are sleeping in seperate bedrooms in his home? I see this as being He is now threatening me with court.
Don’t I have rights to continual with the cancellation when on two different days I confirmed that he was not taking him? won’t the court look down on someone who clearly made plans that defied the court order that he agreed to with legal counsel?
Finally, won’t the court see him as not providing a stable environment since he just got seperated from his current wife and is now engaged to a woman less than 4 months later? The current wife I just found out had numerous psychiatric hospitalizations, drug use and was arrested for DUI a week after she left. My ex also has a history of drug and alcohol. I can not prove current use or misuse though.

I believe separate hotel rooms are considered acceptable by the courts.

Requesting moderators to give some direction.

It is unusual to have a no overnight guests clause that lasts forever. If you don’t believe the present situation is in the best interest of your child then you should file a motion to modify.