cbet stat is not a "cbet in 3bet pot stat" so I think we can discount that.

considering his tight 3b range I like flatting if he's not the type to felt AK.

his bet sizing being huge i can see a fold but i'd probably call one street to see what he does though it looks like we're pretty smoked now. I def wouldn't think of this hand as "KK for set value' as you could be up against a lot of worse hands pre, its more his cbet sizing that is the caution imo