Claim son and claim recovery credit. 

What Ex got (possibly)affects their return, let them worry about that. You are entitled to claim it now if the dependent is yours this year. (and you meet any other requirements)

"how to handle on my return"

You seem to be lost on the internet.

You’ve come to a Peer User community for Intuit Income Tax Preparation products supporting tax preparation professionals using ProSeries, Proconnect and Lacerte Tax Preparation programs, and you may be looking for support as an individual taxpayer using TurboTax. Please visit the TurboTax Help site for support.

Your sign in user info here is the same one you can use over at the TurboTax forum.

Thanks.