He begged for you to fuck him, but he should know by now that you will fuck him on your terms, not his!
Put the strap-on harness around you and secure it so that it is ready for use. Now look at him, blindfolded and kneeling, waiting desperately for your attention. If the shoe were on the other foot, and he was looking for a place to stick his hard cock, your mouth would look pretty tempting...
I think it's time for him to try sucking cock.
Do not be the least bit insulting during this phase. Don't even make jokes. And remember, you will undoubtedly go through a lot of embarrassing stuff both in and out of the bedroom so don't joke or make insults later either. This shouldn't be different from how he treats you for giving him head.
Instead think about how much courage it must take for a man to play this game. It takes A LOT of trust to be this vulnerable. That trust should be empowering for you AND him, and makes the act that much more intimate!