For me, the alarm bells go off with the checkraise on the turn. Why would the guy checkraise after a brick lands on the flop (unless he's a maniac). That was you first opportunity to fold. Then, after another relative brick on the river, and after checking the flop and check-raising the turn, he bets big for the first time this hand.

He has shown considerable strength. So what do you have beat? You have top pair, top kicker so what were you hoping he had so you could beat him? You could beat a pair of 2s, 3s, or 8s. But does his play make sense with an underpair? He might have a pair of Qs but he sure was aggressive with only high card before the river. He could have a pair of Ks with a lower kicker, but again really only a maniac would play with that type of hand like he did. Thus, he had to have at least two pair or the flush.

Thank you for this post. I have probably done the same thing in the past and I will try to rectify that in the future. It's easier to analyze someone else's hand with the luxury of leaning back in your chair and thinking about it rather than in the heat of battle.