Do you think that's going to happen? Has he shown any signs of changing his attitude?
How curious are you about why your husband dislikes this guy so much? Have you asked this guy what he thinks is the reason your husband dislikes him? If you go ahead and have sex with this guy your husband will know that what he wants won't matter. He'll know that HIS no won't be respected. He knows that will open up another opportunity for "the next guy".
If this isn't the first time you've done something sexual directly against the wishes of your husband, and it's part of a kink you two share, then things are different. That would make sense. It still seems like an "edgy" game to play especially if it's done wrong.
If this IS the first time you've done something sexual directly against the wishes of your husband, and it's something you two DON'T agree on, then it seems even more dangerous. If you had to put them in order of excitement, how would you place these three, 1) Going against what you know your husband doesn't want, 2) Fucking someone your husband dislikes, 3) the sex?