What is your sexuality OP? Are you asexual? It doesn't sound so. So are you in agreement that for the rest of your life you won't have sex? What exactly do you and he view as sex? PIV? Anything involving genitals? When did he figure this out vs him telling you?
He's told you about himself, which is good, but it stops being about him now. Unless you're also asexual, in which case this is good news, the person whose wishes now should become highlighted (but not pressured) are yours.
Your reference to promising to stay with him in your marriage vows are redundant. He's basically broken the covenant because he promised to love and cherish you, forsaking all others. Or something similar. Everybody knows that "loving and cherishing" isn't only being attentive and kind, holding hands and cuddling.
You are not obliged to remain in a sexual relationship with someone who will not have sex with you for a reason that wasn't made known to you before getting married, whether or not he knew himself.
You're not obliged to deny your own needs in order to have a friendship. You can, it's totally up to you, but you don't have to.
And I'm not saying leave him. But I am saying that you would not be some kind of bad woman for saying that it's totally ok for him to be asexual, but your sexuality is something different. Just as it's unacceptable for him to be pushed into having sexual relations when he doesn't want to, it's unacceptable to force you into never have them ever again, when you're not asexual.
Effectively the relationship will enable him to live his best life, while you have to suppress an important part of yourself forever. And the only thing in a monogamous relationship that you can't get satisfied elsewhere. It's not something friends, family, work, joining a club can be a substitute for.
I've been through this, only it was me who figured it out (neither of us knew the term for it before) and he didn't want to admit it, but admitted he was the description! I felt so awful for the idea that I'd break the family up because I wanted sex. So I didn't. In the end we divorced for other reasons, but looking ahead to never having sex ever again was exceptionally bleak. How is it for you though?
Btw there are lots of people on here who simply don't believe asexuality is real. They think the man must have a porn addiction or a secret mistress or something. Of course some do. But some people are really asexual too.