[BKiCe]

i don't get it... you say you guys have a lot of history and you've never caught him check-raising the river as a bluff, yet you don't know what to do with a ten high flush on a paired board?

given the information you provided i'd fold without much regret, but if this is ever a call, i don't see how anyone else would be able to tell you so rather than you knowing yourself since you're the one with all the history/experience playing villain

edit: and i would bet this river 110% of the time