[nutstoyou]

When he reraised to $8.50 on the turn, I think calling is the worst option. You have four outs to a full house so, on the river, you will hit only about one in twelve times.

I think you either shove or fold after the reraise to $8.50 on the turn. Based on his position as the CO, I think he played the flop the way a lot of players would with a set.

He was next to last to act after the flop and may have been afraid that if he raised, then the button might not have an A so he would fold, and then everyone else would fold also.

If he had a set then your bet on the turn was exactly what he wanted to see, so he started raising.

I would have folded when he raised to $8.50 unless I had seen him making a lot of late bluffs or raising with weak hands on the turn and river.