Flop second nut straight vs maniac, do I call down?

[Poker monkey]

CO is a lunatic playing 76/46/1.7. He definitely tries to bluff and bully, although usually shows up with a hand in the big pots.

I call on the flop because I have the second nuts. (Should I just fold here?)

On the turn I might lay it down but I have the second nut flush draw to go with it.

The river card doesn't change anytihng. I folded but I don't know, should I have called? Or is it just a "read dependent" jobby?

Pot Limit Omaha Ring game
Blinds: $1/$1
5 players
Converter

Stack sizes:
UTG: $10.10
CO: $412.20
Button: $212.10
Hero: $156.85
BB: $191.80

Pre-flop: (5 players) Hero is SB with 7[img]/images/graemlins/club.gif[/img] K[img]/images/graemlins/club.gif[/img] 5[img]/images/graemlins/club.gif[/img] J[img]/images/graemlins/diamond.gif[/img]
UTG calls, CO calls, Button calls, Hero checks, BB checks.

Flop: 6[img]/images/graemlins/club.gif[/img] 9[img]/images/graemlins/diamond.gif[/img] 8[img]/images/graemlins/spade.gif[/img] ($5, 5 players)
Hero checks, BB checks, UTG checks, <font color="#cc0000">CO bets $5</font>, Button folds, Hero calls, 2 folds.

Turn: 2[img]/images/graemlins/club.gif[/img] ($15, 2 players)
Hero checks, <font color="#cc0000">CO bets $15</font>, Hero calls.

River: K[img]/images/graemlins/heart.gif[/img] ($45, 2 players)
Hero checks, <font color="#cc0000">CO bets $45</font>, Hero folds.
Uncalled bets: $45 returned to CO.

Results:
Final pot: $45