the near begginings of a HU match, tourney style.
I am on the button. Cards are dealt out and I have


. I limp, am rasied and call. Bear in mind, my opponent rarely folds to a raise pre.
flop comes


at this point, my opponent flashes one of his hole cards (Kd) to me by accident while holding them in one hand and stacking chips with the other. I tell him that I believe I just saw the Kd, he confirms by showing me and when asked if we redeal, he says that he will play the hand. Is the hand dead at that point? I don't believe so myself but want clarification for next time. If it is, then from here on out is moot but I shall continue anyway.
Knowing I have him beat and not wanting him to flee, I check, he bets, I call.
turn



2 diamonds now, no King. He checks, I bet out and he flat calls.
river




He leads out with a pot sized bet. My thoughts at the time were, "he knows I saw his diamond, is he repping the flush because he missed completely? was his other card also a diamond? or did he get lucky the other way and river a straight with a KQ o/s? "
What would you have differently throughout the hand and what do you do after the river bet?