Fold KKK on flop after villian check/pushes?

[Tito]

Villian was pretty TAG. He had shown down the best hand almost every time. A pretty decent player IMO. I had just rivered quad 3's to beat a full house a few hands ago. And then this hand came up.

Party Poker ($0.5 no limit). Hand converted by Check Raised hand converter

UTG ($66.45) (UTG)
<u>HERO ($132.92) [ K K ] (CO)</u>
SB ($33.45) (SB)
BB ($20.55) (BB)
BTN ($48.70) (BTN)

Preflop (5 players):
UTG raises $1.00.
HERO raises $4.50.
3 folds.
UTG raises $7.00.
HERO calls ($3.50).

Flop (33.5 bets ($16.75) in pot, 2 players): A 7 K
UTG checks.
HERO bets $8.00.
UTG raises $58.45.

Hero?

Can I really fold here? I asked him after he pushed if he had aces and he didn't respond. I think this is an insta-call but there are only 3 hands he could have here, AA, 77, and AK that would explain his push. I don't think he's pushing with any less here. Opinions??