I agree with awest's suggestion that you should defer any STBX related questions to her unless you think what STBX is telling them is absolutely wrong and will be a bit let down the for the kids. In that case you can tell them 'I think that'll be great if mom can do that however if it doesn't happen it's still OK, we'll be fine'. At least that's what I would do, it'd be hard to watch the kids get their hopes up, make plans and yet you know it ain't gonna happen.
So why do you have to pay her child support if she's making more than you? Unless you have less than 50% custody?
Me: 35|WAW: 38|D: 6yo | http://tinyurl.com/2dxx7m6 Feb 2006, left, came back in two weeks Aug 2006, left again Apr 2007, filed for divorce Dec 2007, reunited Mar 2010, moved out, filed again