My question involves a child custody case from the State of: Colorado

My ex was ordered to pay child support, is behind, and we have a contempt hearing coming up to address this. In the exhibits we exchanged, he included his unredacted 'checkbook' for a time where he wasn't making payments through the State Support Registry. This checkbook details all of the support payments he made to me. Problem is, it is complete non-sense and these checks were never written or sent to me. He just fabricated the whole thing. This is not out of character for him, he has pulled/attempted to pull similar things before in court. There are no bank records, copies of the checks, or correspondence between us regarding them, because they never existed in the first place.

First off, is this admissible as evidence? On what grounds can I object? To make a bad over simplified metaphor, its like being on trial for some crime and is submitting as evidence a self written note saying that he is innocent of said crime. Even if it is admitted there is no way this could count as proof pf payment, right? Thanks for your help.