Well, you have not said which one of you will claim the children as dependent on your 2021 tax return.    If you are not the parent who will claim the child then getting the payments yourself might be  a bad idea for you---you could possibly have to pay the credit back when you prepare your 2021 tax return.   You can opt out of those payments.   If you and your spouse somehow reconcile and get back together and file a joint return you can still get the full child tax credit on your 2021 tax return.

Use this IRS portal to manage payments or unenroll.

https://www.irs.gov/credits-deductions/advance-child-tax-credit-payments-in-2021

The child is not mune nor do I have ny legal right over them. Her mother will claim her but since we did taxes jointly wont her portion the the relief still get sent to me since my bank is the one set up for the direct deposit? I opted out of the child credit to revent me having to owe money when I file as single next year.

She can change her banking information on the IRS portal when it is fully functional---which is supposed to happen by August.  

https://www.irs.gov/credits-deductions/advance-child-tax-credit-payments-in-2021