Big pot, overpair, called down, rethinking

[J. Stew]

About 15 hands in at a loose table. Villain is UTG and has been limp happy and not overly aggressive.

Party Poker 0.50/1 Hold'em (9 handed) converter

Preflop: Hero is UTG+1 with K[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/club.gif[/img]. MP3 posts a blind of $0.50.
UTG calls, <font color="#CC3333">Hero raises</font>, <font color="#666666">1 fold</font>, MP2 calls, <font color="#CC3333">MP3 (poster) 3-bets</font>, <font color="#666666">3 folds</font>, BB calls, UTG calls, <font color="#CC3333">Hero caps</font>, MP2 calls, MP3 calls, BB calls, UTG calls.

Flop: (20.50 SB) T[img]/images/graemlins/spade.gif[/img], 2[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(5 players)</font>
BB checks, UTG checks, <font color="#CC3333">Hero bets</font>, MP2 folds, MP3 calls, BB calls, <font color="#CC3333">UTG raises</font>, <font color="#CC3333">Hero 3-bets</font>, MP3 folds, BB calls, <font color="#CC3333">UTG caps</font>, Hero calls, BB calls.

Villain check-raises, I three-bet because he could be messin' around with AT, though unlikely as he seemed average passive, or maybe a flush draw but I didn't think he would make that play either. Actually I don't know why I raised.

If villain is on a flush draw, is it correct for him to check-raise?

Though villain was loose, he wasn't loose enough to play T2, T3, or 32. I put him on a set after his flop cap.

Turn: (16.75 BB) 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">UTG bets</font>, Hero calls, BB calls.

I put villain on a set, I don't have the odds for a two outer so the reason I'm calling is that I don't believe myself?

River: (19.75 BB) 8[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">UTG bets</font>, Hero calls, BB calls.

Final Pot: 22.75 BB