Probably not. You should have known of the date and time of the hearing, and for whatever reason decided to be driving at that time rather than being somewhere you could hear and focus on the phone call you knew was coming. You were likely placed under oath and questioned, and your answers therefore were and are binding. If you questioned the reasons your ex was giving you to cut this deal, you should have consulted with someone before the actual hearing. In general terms, something you have sworn to under oath at a scheduled hearing cannot later be "undone."
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