@Sturgis,
Sturgis wrote:
You need to contact a lawyer who is familiar with Colorado divorce contracts.
agreed - and in the mean time gather all evidence (receipts, canceled checks, bank statements) of what you paid - also if you emailed, texted, etc anything that you might have that supports you made such an agreement.
It might or might not help your situation but whatever you can provide that supports your agreement with your ex otherwise it could be a "he said, she said" sort of thing with no evidence.
In the future follow precisely what the court orders so you do not get in this situation again. I am guessing you were probably doing what you felt was right by the children which is great, but unfortunately when it comes to money some people can just simply get greedy and take advantage.