Perhaps you can expand on why you find the fetish disgusting? What makes it on the verge of being a dealbreaker for you?

you mention it contributing to his impotency. Have you actually talked about that with him by the way?

Have you stated the fact that this fetish of his is bothering you severely to the point of you considering a break up?

It might benefit to candidly but delicately discuss these things with him, as he might be able to open up on his perspective, maybe even make a conscious effort to the extent that he can.. but I understand the hesitance to be so forthcoming if you're unconfident on how he'll react. Which is why if you are to take this approach, should ideally be met with tact