Surprise River Raise

[Softrock]

40-80 at Bay 101. I'm running very good and have a very strong table image tight but watch out if I'm mixing it up. Fellow on the Button open raises. This is a very tight player who plays OK but I think he's actually too tight. However, he is sophisticated enough to open raise with a variety of hands on the button particularly with my big blind knowing I'm fairly tight. SB folds, I'm in BB and have 5 [img]/images/graemlins/heart.gif[/img]7 [img]/images/graemlins/heart.gif[/img]. I like calling here getting 3 1/2 to one on my bet. The flop comes 6 [img]/images/graemlins/heart.gif[/img]6 [img]/images/graemlins/diamond.gif[/img]5 [img]/images/graemlins/spade.gif[/img]. I bet out, button calls. Turn is 3 [img]/images/graemlins/heart.gif[/img]. I now have a flush draw and a gut shot straight to go with my two pair. I bet again. Button calls. River is 5 [img]/images/graemlins/diamond.gif[/img] so I have fives full of sixes. I bet and the button now raises.

Where am I at and do I re-raise. (I'm assuming nobody is going to advocate folding here).