No. Legally she is NOT obligated to return that money if it was collected per a valid court order, prior to filing for termination of support.
Look, you're in Indiana. You should have been communicating with your lawyer in terms Indiana parenting plans guidelines. I haven't seen any evidence that you are aware that they exist. Here's some light reading:
Indiana Parenting Time Guidelines.
A reasonable person uses the guidelines, and expresses succinctly the legal reasons for deviating from standard parenting time/plans.