Two pair on flush board

Villain 34/5/1 over 100 hands, no other reads

Ultimate Bet No-Limit Hold'em, $.25 BB (8 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Button ($13.05)
SB ($9.10)
BB ($24.25)
UTG ($27.75)
UTG+1 ($7.15)
MP1 ($31.30)
Hero ($36.50)
CO ($26.10)

Preflop: Hero is MP2 with Ahttp://www.flopturnriver.com/phpBB2/...iles/spade.gif, Jhttp://www.flopturnriver.com/phpBB2/...iles/spade.gif.
UTG raises to $0.5, 2 folds, Hero calls $0.50, 3 folds, BB calls $0.25.

Flop: ($1.60) Jhttp://www.flopturnriver.com/phpBB2/...es/diamond.gif, Ahttp://www.flopturnriver.com/phpBB2/...es/diamond.gif, 8http://www.flopturnriver.com/phpBB2/...es/diamond.gif (3 players)
BB checks, UTG bets $5, Hero raises to $12, BB folds, UTG calls $7.

Turn: ($25.60) Khttp://www.flopturnriver.com/phpBB2/...iles/spade.gif (2 players)
UTG bets $15.25 (All-In), Hero???.

Hero made up his mind on the flop and insta-calls.

I'd be interested to know what you guys think Heros thought process should be. I think I have a tendency to put people on too specific of a hand. I had him narrowed down to a few that would logically fit his betting and when the K hit his bet just made sense for a fold for me. I wuss out too much here.

My thought process...
--Villian bets $5.--
That's a bit of an overbet. Hmmm. He's either
a) hoping someone caught something and is overbetting a flopped
flush to disguise it
b) has AK/AQ and really wants to take it down now
c) flopped trips and wants to take it down now before a flush fills.
My hand is pretty good, lets raise and find out how good his is.
Called. Hmmm. Didn't come over the top.
--Ks. Villian All-in.--
Shit. Did he smooth call his flush to let me catch up? Did he just hit his A/K? His smooth call makes it seem less like a bluff. Shit. I can't do it. Fold.

Also what do you think Villians thought proces would be with
Kxd
AK
AQ
JJ/88

To ice it...he had to show me his cards. AQ with no diamonds. Ugh. I'm a wuss.