They look up to you? Well, they can watch you leave too and they can know that they had a hand in ending your marriage. If they have any concern for such things. They sound pretty clueless to me.
They sound pretty fucked up to me.
Hearing relatives joking about sucking and fucking each other and laughing it off is fucked to shit! (yeah I know, through ‘indirect’ teasing, plausible deniability and such. But are we naive kids or adults? Bullshit is still shit).
On the other hand OP, you wrote about the cousin looking up to you and putting you on a pedestal? Is this the same cousin joking about filling holes and blowjobs with your wife we are talking about?
More than looking up and pedestal, seems like the butcher caressing the goose neck, praising her over a chopping bloc, with the knife ready behind his back.
I don’t doubt the family likes you but the over the top incestuous banter as a fun time where you are obviously uncomfortable and you have to leave, signals a great lack of respect in my view.
They’re her family of origin, not yours, don’t be too confident they will ever have your back if it turns out that "filling holes and swallowing body parts " between cousins will ever turn out to be something more than just a very inappropriate and disturbing "joke".
You need to put your self first. They are not going to.