My ex husband and I divorced 8 years ago, and it was in Montana and in our divorce degree I have custody of two children and he has custody of the other two and we both are suppose to have visitations in the summer time but he has not had any contact with my son for 5-6 years and now all of a sudden he is trying to get my son to go to his house for the summer which is not a safe environment my ex is very violent, gambles and drinks and beats up his wife and is very emotionally unstable. I'm wondering what I can do to stop my son from going there? My son is very close to me and my husband and does not even no his biological dad.

Please pay more attention to posting guidelines. There is a Read First sticky in the Children forum (where this was moved from) that directs questions of a legal nature to this forum.

Child abandonment has no application here (note there is a sticky note at the top of this forum that discusses it).

We get similar questions all the time. Eight years ago you agreed to allow two of your children to live with their father. Now, all of a sudden, "is very violent, gambles and drinks and beats up his wife and is very emotionally unstable". While its possible he has changed in 8 years, I suspect not.

The bottom line here is, if you want to change the visitation schedule, you will need to to the court that granted the divorce (unless you both have moved) and file for a change in visitation. You will need to prove your claims that he is a danger to the child.

There are some caveats here, like how old were all the children 8 years ago? The ones he got and the ones that stayed with you. That could have a bearing here.