Practically it all depends on who files first! And yes, he could take you to court — but it would be costly for him.
I’ve seen this happen many times through this stimulus program –mostly spouses stealing stimulus payments destined for an ex-spouse. I’ve talked to the IRS and the Treasury and they can’t get organized to do anything to help the wronged spouse.
But, yes, it is a REFUNDABLE credit so his income doesn’t matter. He would get the cash sent to him. But it is going to be very difficult to put this on a return — because they have already sent the first six months to YOU. Not sure how he would claim the remaining 6 months anyway!
Maybe you could continue to claim, and offer him some cash as a deal. Or just wait till he gets angry enough to actually sue you.