NL100 - tough spot with set on flop

[litemyfire]

btn - 10/5/2.5 over 1000+ hands
MP - 17/6/3.5 over 800 hands

Poker Room skin
No Limit Holdem Ring game
Blinds: $0.50/$1
10 players
Converter

Stack sizes:
UTG: $23.75
UTG+1: $110.55
UTG+2: $71.90
MP1: $131.70
Hero: $166.35
MP3: $133.00
CO: $105.65
Button: $105.60
SB: $108.35
BB: $10.15

Pre-flop: (10 players) Hero is MP2 with 8[img]/images/graemlins/club.gif[/img] 8[img]/images/graemlins/heart.gif[/img]
UTG calls, 2 folds, MP1 calls, Hero calls, MP3 calls, CO folds, <font color="#cc0000">Button raises to $4</font>, 3 folds, MP1 calls, Hero calls, MP3 calls.

Flop: T[img]/images/graemlins/spade.gif[/img] A[img]/images/graemlins/club.gif[/img] 8[img]/images/graemlins/spade.gif[/img] ($18.5, 4 players)
MP1 checks, Hero checks, MP3 checks, <font color="#cc0000">Button bets $11</font>, <font color="#cc0000">MP1 raises to $50</font>, <font color="#cc0000">

Hero ???