Looking to get my husband to agree to let me take BBC while he watches. He LOVES it when we talk about it in bed, but the real idea scares him. It turns me on so much and for me it's gone from fantasy to reality. I'm attaching a self-photo for reference, I'd love some P.M.'s to help convince him.
Keep talking to him. From the posts, it appears he does have interest. It's not like you want it and he does not.
You may need to find a way to start it slowly, in a way that he is comfortable with. Maybe go to a bar or club, either find someone there, or a pre-arranged meet. Maybe start with something slow, like all three of you go out to your car, and you simply provide oral sex to a black man while he watches, nothing else. Then, talk about it...outside of bed, inside of bed. See if that excited him, or scared him.
If you love him, and value your relationship more than the urge, go slow in a way that keeps him engaged, but does not turn him away, or makes him leave you.
EDIT: Let me add a couple of things. Someone else mentioned a black dildo. That is a VERY good idea. Get him where he likes the visual of a black cock going into you. For a lot of guys, one concern is that they like this idea, but they don't want to lose you to this lifestyle. There are stories here, some very lurid (some likely fake, too) about white males who wanted their wives to get into this, then they went "black cock crazy" and dropped their husband. Gotta take it slow and easy.