I'd start with a very candid conversation with my spouse, asking if there are any concerns at all, or what kinds of things might be concerns. I'd give him a chance to set some boundaries.
Also, I firmly believe very, very few people set out to cheat or are okay with cheating as a blind concept, and yet so many people do end up having affairs. IMO, part of the reason that happens is precisely because they think they will never cheat. "Cheaters are assholes, I'm not a cheater and I love and respect my spouse, so I'd never cheat." That means they never think about it as part of their world, which means when things start crossing lines, very gradually, they think nothing of it. And inch by inch, they move forward, until they are so involved in the other relationship that physical cheating takes only the tiniest of nudges. And they may already be having what might be considered an emotional affair.
That doesn't mean I don't think men and women can have meaningful, close friendship. I think it just means that close friendships with someone of a sex/gender to which are are attracted require some background vigilance. Set some very firm boundaries for yourself that you will never, ever cross. Check in periodically and be honest with yourself about whether it is starting to feel different than if would be a friendship with a same-sex person (assuming you are only attracted to the opposite sex/gender). Self-patrol your actions, in an honest, self-aware way and adjust as need, early on before things can go too far. Maybe it will never get to that point, but checking in frequently can assure that.