I remember from SSHE that you should play from the BB against a raise all those hands that you would play for one bet from late position. Q5s is not on my list for that. The hand is mediocre. You have more or less the suitedness going for you. It has little high card value, because of the poor kicker. No straight value at all. And even your suitedness might be expensive, because you are easily dominated. Though it's not that bad. So I would have let go of the hand unless the PFR is a maniac, but you didn't provide any reads.

Postflop is not too bad, I think. The board is paired, yes. That makes a full house or quads possible so your flush might not be good. But normally you dont raise a hand preflop with a 8 in it so he would need to have KK on the flop to really scare you. I might have bet on the flop to see if he raises. It's not too expensive there and it gives you a better picture of how strong he thinks he is.

Then chasing the flush was ok. His river check startles me a little. Maybe he had AcJc and was chasing the same flush as you did. Maybe you were lucky and have outdrawn him. But you shouldn't play too many hands like these, because of the threat of domination.

Regards.