Hi and welcome
What is your hubby's background around you being with other men? Have you guys swung before? My main concern is that he is seeing this on a very surfcae level and caught up in the idea of getting to have sex with another woman. I did this one time years ago...got caught up in the sex side of things which overode other underlying emotions. When those emotions surfaced it almost ended my relationship.
A: he's got to really put himself in the place of knowing you are sleeping with another man and,
B: You've got to hammer in the fact that you want an emotional connection with these people. Let him know your goals now, so he can make an informed decision.
You can't undo things, so move slowly, get him to think beyound his penis (which can temporarily overide everything else in a guys mind) and make sure you are brutally honest in what you want.