Flopped set meets lots of aggression

[UK Raz]

Villain in 20/12 over 80 hands. No history. Btn is a loose donk. I was just about to rr him all in when villain 3bets flop. Does anyone fold this spot?

Poker Stars, $0.50/$1 NL Hold'em Cash Game, 6 Players
LegoPoker Hand History Converter

BB: $164.45
Hero (UTG): $138
MP: $127.85
CO: $29.55
BTN: $99.40
SB: $123.65

Pre-Flop: 3[img]/images/graemlins/heart.gif[/img] 3[img]/images/graemlins/spade.gif[/img] dealt to Hero (UTG)
<font color="red">Hero raises to $4</font>, 2 folds, BTN calls $4, SB folds, BB calls $3

Flop: ($12.50) T[img]/images/graemlins/spade.gif[/img] 6[img]/images/graemlins/spade.gif[/img] 3[img]/images/graemlins/diamond.gif[/img] (3 Players)
BB checks, <font color="red">Hero bets $9</font>, <font color="red">BTN raises to $18</font>, <font color="red">BB raises to $45</font>, <font color="red">Hero ???