Change of agreement threatened

I am divorced. Two kids: girl 9, boy 12. Remarried. Step kids: boy 6, girl 10. Step son has major behavorial issues, constantly disrupting our home life. We are in process of having him evaluated and doing our best. My son has become very depressed and dispondent over the disruptions, as well as the fact his mother lives closer to his established friends, church, etc. My ex and I each have the kids on alternate weeks, for an entire week. I would not agree to our divorce unless we had equal time in the kids' lives, as I was not going to be a "weekend dad". Now my son is saying he wishes to stay with his mother, but see me "when I want to see him". He loves us both the same, but says he cannot take what is going on anymore, though he wants to be with me very much. I have considered counseling for him, and have made compromises to try and make it easier for him, including giving him more time at mom's, in hopes we can eventually get the issues resolved. I do believe my ex is "feeding" the negative emotions of my son, making it worse and more conflicting for him. She is requesting that we change our agreement to say that they stay with her. My daughter is conflicted as she wants to be with her brother. How much of a chance would I have in keeping our agreement as is, but doing all I can to get my son through this difficult time? Or would it be most likely my ex would get her wish to change the agreement? Our agreement was created in Massachusetts, and I live just over the border in NH. Thanks for you input.

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As difficult as it is for him you have a very good chance. Your ex would have to prove that something has dramatically changed but you can certainly argue otherwise. Your son's feelings will be considered but will not be determinative