Playing both sides of the field

Laura • Married to my best friend and I am blessed to be able to be a stay at home Wifey and Mommy to 3 beautiful kids!
My husband and I have a child together and we also have 2 other children from his previous marriage a 16 yr old son and 12 yr old daughter. They live with there mother and for 2 years now they both have been going back and forth saying they want to live with us then they change their minds and stay with her. We pay $1000.00 a month in child support none of the money ever goes to them so on top of paying that we also pay probably about $600 more on stuff that should be handled by their mother. It has ran us in the ground and we know that's our fault by enabling her to be that way. This Summer they came to us again and said they wanted us to reopen the court case from 2013 because they definitely weren't going to change there minds they were tired of how they got treated etc.. So we did exactly what they asked us to do and there mother got served almost 2 weeks ago. Now that Summer is over and she got served she's acting like super mom and I went through both of there phones and my daughter told her friend she wasn't going to hurt her moms feelings by moving and my son said I can't believe my Dad thinks I'm going to move when I get treated like a king at my moms and can still get my Dad to pay for the other stuff I want! Of course this broke my heart, I haven't told my husband yet and I don't know if I should or should I just let him see at court what's going to play out. The other problem I'm having is my husband told them if they decide they don't want to move he won't pay out another penny over the child support. Since I've seen what they said I told him to stop now but he won't because he thinks they want to move, last weekend we barely spoke to each other because his ex got our daughter a new phone that didn't work so he paid the $80 to fix her mess once again! I'm so tired of this going back and forth and I hate what it's doing to him and our relationship. From an outside looking in what would you do?