Way too passive with KK

[OrangeKing]

Alright, I know this was bad. Really bad, in fact. But I'd like to get a better idea of just how badly I played this. I was afraid of JJ or AA, which in retrospect is terrible...at least I didn't fold.

Party Poker 0.5/1 Hold'em (8 handed) converter

Preflop: Hero is CO with K[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/club.gif[/img]. Hero posts a blind of $0.5.
UTG calls, UTG+1 folds, <font color="#CC3333">MP1 raises</font>, MP2 calls, <font color="#CC3333">Hero (poster) 3-bets</font>, Button folds, SB folds, BB calls, UTG calls, MP1 calls, <font color="#CC3333">MP2 caps</font>, Hero calls, BB calls, UTG calls, MP1 calls.

Flop: (20.50 SB) J[img]/images/graemlins/diamond.gif[/img], 5[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(5 players)</font>
BB checks, UTG checks, MP1 checks, MP2 checks, Hero checks.

Turn: (10.25 BB) 5[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(5 players)</font>
<font color="#CC3333">BB bets</font>, UTG folds, MP1 calls, <font color="#CC3333">MP2 raises</font>, Hero calls, BB calls, MP1 calls.

River: (18.25 BB) 6[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, MP1 checks, <font color="#CC3333">MP2 bets</font>, Hero calls, BB calls, MP1 calls.

Final Pot: 22.25 BB

I'm normally not this passive - what happened? I didn't bet the flop, by the way, because I knew it wouldn't protect my hand at all, so I can explain that...but the turn and river make me sick.