Capped by Lag-KK in the BB

[zephed56]

MP is a lag who has previously 3-bet me preflop TWICE. This is in about 50 hands or so. I'm not too sure what to do here against aggro opponents. Should I have bet the river?

This site has a lot of lags btw.
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PokerRoom 2/4 Hold'em (5 max, 5 handed)

PRE-FLOP: zephed56 is BB with K[img]/images/graemlins/diamond.gif[/img] K[img]/images/graemlins/club.gif[/img]
1 fold, <font color="red">MP raises</font>, 2 folds, <font color="red">zephed56 3-bets</font>, <font color="red">MP caps</font>, zephed56 calls.

FLOP: J[img]/images/graemlins/spade.gif[/img] 8[img]/images/graemlins/club.gif[/img] A[img]/images/graemlins/spade.gif[/img] (8 SB's)
zephed56 checks, <font color="red">MP bets</font>, zephed56 calls.

TURN: 7[img]/images/graemlins/heart.gif[/img] (5 BB's)
zephed56 checks, <font color="red">MP bets</font>, zephed56 calls.

RIVER: 5[img]/images/graemlins/diamond.gif[/img] (7 BB's)
zephed56 checks, <font color="red">MP bets</font>, zephed56 calls.</font>

[Trix]

I think its fine when you cant fold to a raise.