Party 10/20 - confusing KK hand

[innebandy]

What's the river play? How did I do up to that point?

Party Poker 10/20 Hold'em (9 handed)

Preflop: Hero is MP3 with K[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/diamond.gif[/img].
UTG calls, UTG+1 folds, MP1 calls, MP2 folds, <font color="CC3333">Hero raises</font>, CO folds, Button folds, SB folds, BB folds, UTG calls, MP1 calls.

Flop: (7.50 SB) 8[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/heart.gif[/img], 3[img]/images/graemlins/club.gif[/img] <font color="blue">(3 players)</font>
<font color="CC3333">UTG bets</font>, MP1 calls, <font color="CC3333">Hero raises</font>, UTG calls, MP1 calls.

Turn: (6.75 BB) 8[img]/images/graemlins/diamond.gif[/img] <font color="blue">(3 players)</font>
UTG checks, MP1 checks, Hero checks.

River: (6.75 BB) 8[img]/images/graemlins/heart.gif[/img] <font color="blue">(3 players)</font>
<font color="CC3333">UTG bets</font>, <font color="CC3333">MP1 raises</font>