I can't fold

[aba20]

I am a limit player picking up no limit and I suck at folding 1-pair hands. What is the best line for this hand?

Party Poker No-Limit Hold'em, $ BB (6 max, 6 handed) pokerhand.org hand converter

CO ($106)
Hero ($153.20)
SB ($64.30)
BB ($118.10)
UTG ($71.50)
MP ($95.80)

Preflop: Hero is Button with A[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/diamond.gif[/img]. SB posts a blind of $0.50.
UTG calls $1, MP calls $1, CO calls $1, <font color="#CC3333">Hero raises to $6</font>, <font color="#666666">2 folds</font>, UTG calls $5, MP calls $5, CO folds.

Flop: ($20.50) A[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/club.gif[/img], T[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, MP checks, <font color="#CC3333">Hero bets $18</font>, UTG folds, <font color="#CC3333">MP raises to $36</font>,

Hero????