bad card on the river facing big bet

[LAgambol]

10/20 NL
villian is very loose pre flop, calls almost anything pre with any two cards. tightens up a little post flop, but still incredibly loose. call station type but definitely takes unconventional lines
Hero has been playing semi-LAG, tighter than usual
effective stacks 3K

five handed
Hero on button with A [img]/images/graemlins/club.gif[/img]5 [img]/images/graemlins/club.gif[/img]
Hero bets 70, SB folds, villain in BB calls

Flop:
2 [img]/images/graemlins/diamond.gif[/img] 3 [img]/images/graemlins/club.gif[/img] 4 [img]/images/graemlins/spade.gif[/img]
villain checks, hero bets 100

Turn: Q [img]/images/graemlins/heart.gif[/img]
villain bets 100, hero raises to 400, villain calls

River: 5 [img]/images/graemlins/heart.gif[/img]
villain bets 1500