Ignore it. It is not taxable or deductible to you or your ex.
However, if these payments are coming from a tax-advantaged source, like a pension or IRA, then you don't want to pay the income tax on the full amount, only to turn over a portion tax-free to your ex. You need to get a QDRO -- qualified domestic relations order -- from the court and give it to the pension payer or IRA custodian. That way, your ex will get a 1099-R for the part paid to them, and you only get a 1099-R for the part paid to you.
