what do you do when he says “i’m cumming”?

so if you’re the one controlling your guy’s orgasm, aka doing all the work for him (via HJ, BJ, riding, etc.) and he tells you he’s about to cum, what are you supposed to do? sometimes in the moment i get so distracted by how hot that phrase sounds that i’m pretty sure i’ve just kinda froze. but i know stopping is the worst thing you could do! so do you just keep going at it until he’s finished? should i keep the same pace or does slowing down feel better for him?